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AATARI 130XE

PERSONAL COMPUTER

OWNER’S MANUAL

IMPORTANT INFORMATION

Like any electrical appliance, this ATARI 130XE Computer uses and produces radio¬
frequency energy. If it is not installed and used according to the instructions in this
guide, the equipment may cause interference with your radio or television reception.

If you believe that this equipment is causing interference with your radio or television
reception, try turning the equipment off and on. If the interference problem stops when
the equipment is turned off, then the equipment is probably causing the interference.
With the equipment turned on, you may be able to correct the problem by trying one or
more of the following measures:

• Reorient the radio or television antenna.

• Reposition the equipment in relation to the radio or television set.

• Move the equipment away from the radio or television.

• Plug the equipment into a different wall outlet so that the equipment
and the radio or television are on different branch circuits.

If necessary, consult your ATARI Computer retailer or an experienced radio and
television technician for additional suggestions.

Another helpful resource is How to Identify and Resolve Radio-TV Interference
Problems, a booklet prepared by the Federal Communications Commission. This booklet
is available from the U.S. Government Printing Office, Washington, DC 20402, Stock No,
004-000-00345-4.

WARNING: This equipment has been certified to comply with the limits for a Class B
computing device, pursuant to Subpart J of Part 15 of FCC Rules. These rules are
designed to provide reasonable protection against such interference when the
equipment is used in a residential setting. However, there is no guarantee that
interference will not occur in a particular home or residence. Only peripherals (computer
input/output devices, terminals, printers, etc.)-that have been certified to comply with
the Class B limits may be attached to this computer.

Operation of noncertified peripherals with this computer is likely to result in interference
with radio and TV reception.

Every effort has been made to ensure the accuracy of the product documentation in
this manual. However, because we are constantly improving and updating our computer
software and hardware, Atari Corp. is unable to guarantee the accuracy of printed
material after the date of publication and disclaims liability for changes, errors, and
omissions.

ATARI, ATARI BASIC, 400, 800, 1010, 1050, 65XE, 130XE, 800XL, XE, XM301
XMM801, XDM121, XTC201, and XTM201 are trademarks or registered trademarks of
Atari Corp.

No reproduction of this document or any portion of its contents is allowed without the
specific written permission of Atari Corp., Sunnyvale, CA 94086.

A ATARI*

AATARI 130XE

PERSONAL COMPUTER

The Right Computer
for the Task at Hand

Welcome to the world of personal computing. Your new
ATARI® 130XE™ is one of the most powerful and versatile small
computers you can buy.

The 130XE is the newest addition to the XE™ series of ATARI Com¬
puters. With 131,072 bytes of Random Access Memory, the 130XE has
twice the memory of the ATARI 65XE™ or the 800XL™ Computer. And
with twice as much memory, the 130XE has more computing power
and more potential. Your word processing files can be longer, your
data files larger, and the educational uses of your computer system
more advanced.

Along with the extra memory, the 130XE has a full-stroke keyboard,
superior sound and graphics capabilities, thousands of available
software programs, and an array of compatible hardware accessories.
The ATARI 130XE is the perfect computer for business, educational,
and entertainment purposes. And the new 130XE comes with built-in
ATARI BASIC programming language, so you can immediately begin to
write your own programs.

This manual is arranged for easy access to the information you need,
whether you are a beginning or an advanced computer user. Part 1
shows you how to unpack and set up your ATARI 130XE Computer,
check whether it’s functioning properly, use the keyboard, load
software cartridges, and expand the system by adding peripheral
devices.

Part 2 is an introductory lesson in BASIC programming. Your ATARI
130XE has many applications, and understanding its built-in language
will make your computer more fun and more useful.

If you already know how to program, you should look at Part 3 of the
manual. A variety of sample programs and the reference materials to
enhance your programming skills are provided. And the advanced
programmer will find the needed information to access the full RAM
potential of the 130XE.

Once you have the ATARI 130XE set up and working, look at the
Resources section of the manual. There are unlimited resources for
the ATARI Computer owner—from books and programs to users
groups and magazines. You’ll find a whole realm of new activities and
uses for your ATARI Computer.

Table of Contents

PART 1: GETTING STARTED

Meeting the ATARI 130XE . .

Hooking It Up
Checking It Out

Understanding Your Keyboard . .... i

Introducing ATARI Graphics 17

Adding an International Character Set ... .19

Exploring ATARI BASIC ... 21

Using Software 23

Expanding Your System 25

PART 2: PROGRAMMING WITH ATARI BASIC . 27

Editing with the ATARI 130XE Keyboard ....... 29

Writing a Simple BASIC Program:

NEW, LIST, PRINT, RUN ... 35

Creating an Interactive Loop:

GOTO, DIM, INPUT . 41

Using Random Numbers and Mathematical Functions:

RND, + 47

Making Decisions and Solving Problems:

IF-THEN, FOR-NEXT . 55

Producing Sound and Graphics:

SOUND, SETCOLOR, COLOR . . 65

PART 3: APPENDICES . 77

A. Sample Programs .79

B. BASIC Reserved Words. . . . . .... 93

C. ATASCI I Character Set .101

D. Error Messages 111

E. Troubleshooting .115

F. Resources 117

G. ATARI 130XE Specifications 119

H. Accessing the Full RAM Potential of the 130XE 121

I. Connector Pinout Specifications. 123

INDEX

. 127

CM LO O) 00

Parti

Getting Started

Meeting the ATAR1130 XE

Keyboard

Full-stroke design with access to 62 keys including the Help key and 4
special function- keys.

♦ * 0 Peripheral Port

Connects a Serial I/O cable to peripheral equipment, such as disk
drives, program recorders, printers, and modems.

^ Cartridge Slot

Allows the use of plug-in software cartridges for quick and easy
program loading.

Expansion Enhanced Cartridge Interface (ECI)

Connects high-speed peripherals such as fast floppy disk drives, hard
disk drives, and custom I/O devices.

^ Monitor Jack

Connects a monitor cable for use with either a monochrome or color
monitor.

i j

(tjp TV Channel Select Switch
Selects channel 2 or 3 for the clearest picture.
Television Jack

Provides a plug for the TV Video Cable.

Power Adapter Plug

Connects the computer to the AC power supply.
10 On/Off Switch

Turns the power to the computer on and off.

Controller Ports

^ Controller Ports

Connects touch tablets, numeric keypads, joysticks, and paddle
controllers. Use Port 1 if only one controller is used.

Hooking It Up

When you unpack your ATARI 130XE, make sure you have the
following items:

• ATARI 130XE Computer

• AC Power Supply

• TV Switch Box

• TV Video Cable

• 130XE Owner’s Manual

• Warranty/Registration Card

If you are missing any of these items, contact your dealer. (Your
warranty covers missing items.) Another good idea is to save the
packing materials in case you want to transport the computer or send
it in the mail.

Setting up your ATARI Computer system is easy. All you need is a
television set and a screwdriver. Your ATARI 130XE can be connected to
an ordinary black-and-white or color television, or you can buy a computer
monitor to use solely as a display screen.

To connect the computer to a monitor, follow the installation
instructions that come with the monitor. You will need a connecting
cable (usually supplied with the monitor) to attach the monitor to the
ATARI 130XE Monitor jack on the back of your computer.

If you are going to use a television as a display screen, locate the TV
Switch Box and the TV Video Cable. The Switch Box attaches directly to
your television, but it will not interfere with normal television reception.
With the sliding switch in the COMPUTER position, your television will
display signals from your ATARI 130XE. In the TV position, signals
come from your television antenna.

INSTALLING THE TV SWITCH BOX

How you install the Switch Box will depend on the kind of antenna
connection that you have. There are two types of connections: a
round, 75-OHM connection and a flat, 300-OHM twin-lead connection.
Follow the steps below for either type of antenna connection:

1 . Disconnect your present VHF antenna or your cable TV line from
the terminals on the back of your television. If the antenna cable is the
75 -OHM round variety with a screw-on connector, attach it to a

75-OHM to 300-OHM adapter and then attach the adapter to the screw
terminals on the bottom of the TV Switch Box. (You can purchase the
adapter at a video or television store.)

-C3C£>

Adapter

If the antenna cable is a flat twin-lead 300-OHM cable, attach it to the
screw terminals on the bottom of the TV Switch Box.

2. If your television has a threaded VHF connection, attach a threaded
VHF adapter to the twin-lead cable labeled Connect to TV VHF at the
side of the Switch Box and attach it to your television. (The adapter
should be supplied with your television; if not, you can buy one at a
video or television store.)

COMPUTER

If your television has two VHF screw terminals, attach the twin-lead
cable labeled Connect to TV VHF at the side of the Switch Box directly
to the VHF terminals on your television.

J2—

COMPUTER

CONNECT
TO TV
VHF

UHF

<S> <S>

VHF

(SMS)

Television

CONNECT TO MITtNNt

\ /

Note: If the terminal connections on your television are different from
those shown, refer to the television manual or contact a service center.

3. Remove the cover from the adhesive square on the back of the
Switch Box and secure the Switch Box to the back of the television.

CONNECTING THE COMPUTER TO THE TV SWITCH BOX

4. Plug one end of the TV Video Cable into the COMPUTER connection
on the TV Switch Box and the other end into the Television jack on
your computer. Move the sliding switch on the TV Switch Box to the
COMPUTER position.

TV Video Cable

5. With the power switch on the computer in the off position, insert the
round plug of the AC adapter into the Power jack on your computer.
Plug the other end into an electrical outlet.

6 . Turn on your television and select channel 2 or 3, whichever is
weaker in your area. Set the Channel switch on the back of your com¬
puter to the same channel. Turn on the power switch of your com¬
puter. In a few seconds you will see the word READY.

The Ready prompt tells you that ATARI BASIC is ready for your instruc¬
tions and that your computer is hooked up properly. If the Ready prompt
does not show up on your screen, try adjusting your television picture
controls. (For more information, see Appendix E: Troubleshooting.)

When you leave your computer on for more than nine minutes without
using the keyboard, the computer will start changing colors to protect
the television from “color burn.’’ Whenever you turn your computer
off, wait a moment before turning it on again.

CARING FOR YOUR ATARI 130XE

• Wipe off dust with a moist, lint-free cloth.

• Do not use household solvents or cleansers on the computer.

• Keep liquids away from the work area.

• Avoid smoking near the computer.

• Don't move the computer more than is necessary.

Checking It Out

When you turn on your ATARI 130XE, it automatically tests itself. But
you can run three separate tests just to insure that your computer is
working properly. Running all three tests after setting up your com¬
puter for the first time is recommended. To run the tests, turn the
computer on while you are holding down the I Option | key. You may
also get to the test program by typing BYE when ATARI BASIC gives
the Ready prompt. (If you have a disk drive hooked up to your com¬
puter, make sure it is turned off when you run the Self Test.)

A Self-Test menu will appear on the screen. Like a restaurant menu,
this menu offers a choice of selections: MEMORY TEST, AUDIO¬
VISUAL TEST, KEYBOARD TEST, and ALL TESTS. Press I select I to
choose a test, then press (start]. Press ITieipl at any time to return to
the Self-Test menu. When you select ALL TESTS, the computer runs
all three tests for you. The tests repeat until you press the I Help | key.
Press I Reset I to stop the tests and return to ATARI BASIC.

MEMORY

AUDIO-VISUAL
KEYBOARD
ALL TESTS

MEMORY TEST

This test checks Read Only Memory (ROM) and Random Access
Memory (RAM). ROM is noneraseable memory containing the com¬
puter’s operating system. RAM is the memory for the programs that
you use or write yourself.

The Memory Test works a little like a stoplight. Two bars appear on
the screen when the ROM is tested. If the bars turn green, the ROM is
okay, and you may proceed. Red means stop; the ROM is out of order,
and you must contact your ATARI retailer.

During the RAM test, 48 kilobytes(K) of RAM are tested. Each of the
48 small squares represents one K of RAM. If a square turns white,
then green, the corresponding section is good. If a square turns red,
the RAM section is not working.

Note: If you enter the test program from ATARI BASIC by typing BYE,
you’ll get 40 small squares during the Memory Test, not 48. ATARI
BASIC takes up the other 8K of RAM.

AUDIO-VISUAL TEST

The Audio-Visual Test checks the four programmable sound voices
and the color and graphics capabilities. A musical staff and treble clef
appear on the screen above the number of the .voice being tested. Six
notes are played and displayed on your screen. The six notes repeat
once for each of the four voices.

If a voice number appears but you don’t hear music, that voice is not
working properly. Make sure that the volume on your television is
turned up. If you are using a monitor, make sure the audio cable on
the monitor is firmly attached.

The colors displayed on the screen should be consistent during each
test.

THE KEYBOARD TEST

When you select this test, you work with two keyboards—the one
under your fingertips and a test keyboard on the screen. When you
press a key, a corresponding key on the screen flashes in inverse
video (a blue character on a white background), and a note sounds.
The space bar and special-function keys are already in inverse video,
so pressing any of them changes the matching key on the screen to
normal video. The I shut I and I control | keys flash only when they are
pressed simultaneously with another key.

%1234S67890<> IDE

VT1 QWERTYUIOP- - d]
a A 5 D F G H J K L ; + * 0

Id IZH CVBNH

Look at the keys on the top row of the test screen keyboard. Each key
except the 4 numbered keys represents a key on your keyboard.
Reading from left to right, the keys in the top row include I Reset 1 . 1 start I ,
I select I | Option I , four numbered keys, l Heipl . Inverse Video, and I Break I

There are two keys that do not flash or sound and that terminate the
test when they are pressed: I Help I returns you to the Self-Test menu;

I Reset I returns you to BASIC. The I Break I key does not function in the
Self Test and evokes no response when pressed. If any key, except
the l Break l key, does not flash on the screen when you press a key,
the key is not working.

In addition to the optional Self Test, your ATARI 130XE automatically
tests itself each time you turn the computer on. If the computer’s
circuits fail the test, your screen will display the words MEMORY
TEST, along with red and green squares and rectangles. As long as
you experience trouble-free operation, running the Self Test every few
months should be sufficient.

LOADING SOFTWARE CARTRIDGES

To load a software program that you have purchased, make sure that
the computer is turned off, hold the cartridge so that the label is
facing up, push the cartridge firmly into the Cartridge slot on the back
of the computer, and turn on the computer. If you have already been
using another software program, turn off the computer, remove the
first cartridge, insert the new cartridge, wait several seconds, and turn
on the computer again. (For more information about software
cartridges, see Using Software.)

If you don't want to use ATARI BASIC (the programming language that
is built into your ATARI 130XE), you can temporarily disable the
language in several ways: plug in a software cartridge; hold down the
I Optionl key when you turn on the computer; type BYE to exit to the
Self Test; or, if the computer is connected to a disk drive, type DOS to
activate the Disk Operating System. (For more details, see Exploring
ATARI BASIC.)

Understanding Your Keyboard

Although the ATARI 130XE keyboard looks and works much like a
typewriter, some special keys allow you to reach into a bag of special
editing tricks. Some of the keys, like I Shift I and I Control l . are used in
combination with other keys. These double-key combinations provide
extra commands and functions without-increasing the size of the
keyboard.

The following general descriptions explain the special keys and how
they are used. Because the function of a key may change from one
program to another, it is important to consult the manual that accom¬
panies each program you use. For a detailed description of how the
keyboard functions with built-in ATARI BASIC, see the chapter Editing
with the ATARI 130XE Keyboard in Part 2: Programming with ATARI
BASIC.

Gives you instructions in some
programs when you need help.

Start

Usually tells the computer to
begin running a game or a pro¬
gram. Consult the software
manual.

Often used to select one of
several applications within a
program. Because its function
varies, consult the software
manual.

Temporarily disables BASIC when
pressed as the computer is turned
on. In some programs, chooses
among program variations.

Pressing | Reset I produces the
same effect as turning the com¬
puter off and on again—with two
exceptions. First, in most pro¬
grams l Reset I will not erase the
computer’s RAM memory, where¬
as turning the computer off and
on will. And second, use of the
I Reset I key will save wear and
tear on the power supply and the
on/off switch.

Esc

Varies from program to program
but is often used to go (escape)
from one menu to another.

Delete
Bk Sp

In most programs, including
ATARI BASIC, deletes (erases)
the character to the left of the
cursor and moves the cursor
one space to the left. Does not
close up the space caused by
the deletion.

Break

Stops the computer in the middle
of an activity and returns the pro¬
gram to the opening screen.

i^—^

Usually interrupts whatever
function the computer is doing.
Refer to individual program in¬
structions.

Control

Return

Tells the computer that you are
done typing or editing a pro¬
gram line. Returns the cursor
to the left margin.

In most programming languages,
stops and restarts a moving
screen display when you want to
view a listing.

Shifts the computer between up¬
percase and lowercase character
modes in ATARI BASIC and other
programs. Sometimes used in
conjunction with the I Shift I key to
change modes. In ATARI BASIC,
exits from the Control Lock
(graphics character) mode.

Turns the Inverse Video mode
on and off. On ATARI* 400™
and ATARI® 800™ models, this
key was referred to as the
ATARI logo key [XI

\- 7

v J

Q \

Sounds the buzzer. (The TV
speaker must be turned up for
the buzzer to be heard.)

Control

Produces an end-of-file (EOF)
response to a program that is
reading input from the keyboard.
(Used by more experienced pro¬
grammers.)

Always used in conjunction with
another key. Prints special gra¬
phics characters when used with
the alphabet keys in ATARI BASIC.

Control

K=^\

Insert

—Si

Inserts a space between char¬
acters in ATARI BASIC, although
its use varies from program to
program.

Deletes the character under¬
neath the cursor and shifts the
remaining characters on the
line to close up the empty
space.

In conjunction with other keys, 9

types uppercase characters
without leaving the lowercase
mode.

Control

When used with the I Control | key,
the arrow keys move the cursor
up, down, left, and right.

Shift

Insert

Inserts a blank line in ATARI
BASIC.

v_ J

V \

Q \

0 -

l i

/ \

screen. The program statement
remains in the computer’s memory.

Control

Caps

Shift

Caps

Locks the computer into the Con¬
trol mode. Used when entering a
series of commands that require
pressing the I Control 1 key, such as
creating graphics characters in
ATARI BASIC.

Locks the computer into the up¬
percase mode for alphabet
characters. You will still need to
press I shift I to enter the upper¬
case mode on the numeric and
symbol keys.

Most keys on the 130XE will automatically repeat when they are held
down for more than half a second.

Introducing ATARI Graphics

The ATARI 130XE keyboard has 29 built-in graphics characters. They
can be used to brighten up a chart or to create a work of art. To
display the graphics characters on your screen, press the | control I key
and any of the keys shown below. If you intend to use several
'characters, it may be more convenient to lock in the Control mode by
pressing I Control I and I Caps I . Press I Caps I to exit from the Control
Lock mode and return to alphabet characters.

Adding an

International Character Set

Ordinarily when you type pages in a foreign language, you go back
and laboriously add accent marks, cedillas, and other diacritical marks
by hand. You are spared that trouble with the ATARI 130XE Computer,
which has an international character set.

International characters are available when you use ATARI BASIC. The
diagram below shows the international characters that are associated
with the letter keys. To activate the international characters, type the
statement below and press the | Return | key:

POKE 756^204

Pressing I Control | and any of the keys shown below will produce an in¬
ternational character instead of a graphics character. To return to the
graphics character mode and normal keyboard utilities, type the
following line and press the I Return I key:

POKE 756/224

Exploring ATARI BASIC

Your ATARI 130XE Computer has built-in ATARI BASIC, a version of
one of the most popular programming languages. BASIC (Beginner’s
All-purpose Symbolic Instruction Code) was developed at Dartmouth
College in the 1960s to teach computer programming to beginning col¬
lege students. Since then, it has become the most commonly used
programming language for home computers.

Although BASIC is a single language, each version of BASIC language
is slightly different, and ATARI BASIC has some important and unique
features. For instance, special words in ATARI BASIC make producing
sounds and creating color graphics easy. Also, ATARI BASIC is
specially designed for the beginning programmer. Unlike'many ver¬
sions of BASIC, ATARI BASIC will check each program line that you
write and tell you if you have made an error in grammar or syntax.

And, of course, when you learn to program with ATARI BASIC, learning
other versions of BASIC will be easier.

ATARI BASIC is immediately available when you turn on the computer.
If you don’t want to use BASIC, hold down the | Option 1 key when you
turn on the computer. Another way to exit from BASIC is to type BYE,
which activates the Self Test, or DOS, which activates the Disk
Operating System (when the computer is connected to a disk drive).

The second part of this manual, Programming with ATARI BASIC, is a
simple tutorial for the first-time BASIC programmer. Unlike most
tutorials, which make you study the syntax of the language first, this
approach lets you immediately begin to write programs and word
games, solve mathematical problems, and make use of the ATARI
130XE sound and graphics capabilities. When you complete this step-
by-step lesson, you will understand much better the functions of the
keys and the workings of the computer. The tutorial will help you get
the most out of your new ATARI 130XE.

If you already know how to program in BASIC, the appendices give
you most of the reference tools you will need to work at your own
speed. Appendix A: Sample Programs includes programs of varying
levels of difficulty to give you some practice before you start writing
your own programs with ATARI BASIC. Appendix B: BASIC Reserved
Words offers a list of the commands used in ATARI BASIC and a brief
description of what each one instructs the computer to do. For
advanced-level programmers, Appendix C: ATASCII Character Set lists

the decimal and hexadecimal locations of characters in the ATASCI I
code. Also, for programmers who want to explore the entire memory
capabilities of the 130XE, Appendix H: Accessing the Full RAM Poten¬
tial of the 130XE gives the formula for POKEing a bank of memory.
Whenever Error messages appear on the screen, you can refer to
Appendix D: Error Messages to find out what went wrong. Check
Appendix F: Resources for the names of other valuable sources of in¬
formation about ATARI BASIC.

Using Software

Your ATARI 130XE and your television are the hardware components
of your system. Software refers to the computer programs that tell
your ATARI 130XE what to do and how to do it. Some software pro¬
grams are built into your computer, some you can buy, and some you
can write yourself.

BUILT-IN SOFTWARE

Built-in software is permanently stored in the Read Only Memory
(ROM) chip inside the computer. Your ATARI 130XE contains a ROM
chip encoded with the ATARI BASIC programming language and the
Operating System program. The Operating System in the ATARI 130XE
contains programs that allow the keyboard, display screen, program
recorder, and most ATARI printers to communicate with one another.

COMMERCIAL SOFTWARE

Commercial software programs are written by Atari Corp. and by
professional programmers and are available from retail outlets. Video
games, spreadsheet programs, word processing programs, and
programmed math lessons are just a few of the many types of
software available for business and educational applications, and for
entertainment.

The ATARI 130XE is completely compatible with the 65XE and the
800XL Computers. You select whatever software program you want to
use, as long as it is designed for use with any of these computers.

Your ATARI 130XE is equipped to use software cartridges. If you want
to use software in diskette or audiocassette form, you will need to pur¬
chase a disk drive or a program recorder.

Note: Some software programs written by non-Atari software
developers for the earlier ATARI® 400™/ 800™ models may not work
with your ATARI 130XE. If you have a disk drive, this problem can be
remedied with a Translator Disk. The disk is available from ATARI
Customer Relations, Atari Corp., P.O. Box 61657, Sunnyvale, CA
94088. Cost: $9.95 plus $2.50 for shipping. California residents add 6.5
percent tax.

USER-WRITTEN SOFTWARE

Once you learn a programming language, you can write your own pro¬
grams. The ATARI 130XE comes with the ATARI BASIC programming
language already built into the computer. The tutorial in Part 2 of this
manual teaches you how to use this language to write BASIC pro¬
grams. However, you can write programs with other computer
languages, such as ATARI Logo, by inserting a cartridge containing
the programming language of your choice.

SAVING YOUR WORK

If you write your own programs, you will probably want to store them
so that you can use them again. And if you use your computer for
word processing, you will probably want to save that work, too. Just
turning off the computer will automatically erase your work from the
computer’s memory, but connecting a disk drive or a program
recorder to your computer enables you to store and retrieve your work
later. The disk drive saves information on magnetic diskettes, and the
program recorder uses ordinary blank audiocassettes. The instructions
that come with the disk drive and the program recorder will tell you
how to use these devices. (For more information, see Expanding Your
System.)

LOADING SOFTWARE CARTRIDGES

Loading ready-to-use commercial software cartridges into the ATARI
130XE is a simple operation. Software that comes in a cartridge is in¬
serted into the Cartridge slot at the back of the computer console.

First make sure that the computer is turned off. Inserting or removing
a cartridge while the computer is on can damage the computer and
the cartridge. Hold the cartridge with the label facing upward. Insert
the cartridge securely into the slot. Then turn the computer on. If you
have just been using another cartridge, wait a moment between the
time you insert the new cartridge and the time you turn the computer
back on.

Expanding Your System

Your ATARI 130XE Computer is the center of a powerful and versatile
system. Whatever job you need to do or game you want to play, the
130XE has a peripheral to help. The most popular peripherals are il¬
lustrated below.

Program Recorder

Printer

Monitor/Television

Computer

Modem

Disk Drive

TV OR MONITOR

A TV or monitor is the display screen for your computer. Many people
prefer to use a monitor because it provides a sharper picture and does
not conflict with television usage. Either a color or monochromatic
(black-and-white) monitor or television can be used. However, many
software programs are designed to showcase the colorful graphics of
the ATARI 130XE Computer.

DISK DRIVE

An ATARI 1050™ disk drive lets you store and retrieve programs and
other information that you create on your computer. Also, because
many programs are available in diskette form, the disk drive provides
access to an extended library of ready-to-use programs in the areas of
word processing, financial management, education, and entertainment.

PROGRAM RECORDER

The ATARI 1010™ program recorder is an inexpensive storage device.
Like a disk drive, it lets you save programs and other information.
Although not as efficient as a disk drive for business and professional
use, it does provide access to a library of ready-to-use educational
and entertainment programs.

PRINTER

As an ATARI Computer owner, you have a variety of printers to choose
from. The XTM201™ and XTC201™ are non-impact, dot-matrix printers
available for your 130XE. Both printers can print graphics; the XTC201
prints in color. To print out reports and letters, graphics, and your
computer programs, you can use the XMM801™, a high-quality,
inexpensive, dot-matrix printer. And for printing professional looking
business letters, you can use the XDM121™, a letter-quality, daisy
wheel printer.

MODEM

With the ATARI XM301™ modem, your computer, and a telephone line
you have access to a wide world of electronic communications. If you
and a friend have modems connected to your computers, you can
send letters to each other. And if you are connected to some of many
data base and information services that are available, you can take
advantage of electronic mail services, news services, reference
materials, and user groups.

JOYSTICK

Joysticks are popular tools for entertainment and educational pro¬
grams. Using a joystick, you can control your computer without
touching the keyboard.

Part 2

Programming

Editing with

the ATARI 130XE Keyboard

No matter how well you type on a typewriter, you will need to
familiarize yourself with the special features of the ATARI 130XE
keyboard before you begin editing with ATARI BASIC.

AUTO REPEAT FUNCTION

Begin by typing the letter A:

Continue to hold down the 3 key and watch the rows of A’s appear.
When a line is filled, the cursor automatically drops down to the next
row. There is no need to press I Return I .

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

You are using the built-in auto repeat function of the ATARI 130XE
keyboard. Most of the keys, including the space bar, have auto repeat.
Did you hear a buzzer when the A’s almost filled the third line? That
warning buzzer—a built-in function of ATARI BASIC—indicates that
the instruction line is getting too long. An instruction line can be no
more than three lines long.

ERROR MESSAGES

Find the I Return 1 key and press it. You should see the word ERROR on
the screen, followed by the three lines of A’s that you typed. Your
computer is interacting with you now. It is telling you that it doesn’t
understand what you are typing because the rows of A's aren’t part of
the BASIC language. Clear your screen by pressing I Return I until the
Error message no longer appears. To avoid getting Error messages
while yo u are following the directions for editing, do not press the
I Return | key until you are instructed to do so.

UPPERCASE AND LOWERCASE

To make lowercase A’s, press the I Caps I key once and hold down the
5] key. You should see this:

aaaaaaaa

To return to uppercase letters, press the leaps] key and type more A’s.
You should see this:

aaaaaaa

Try typing a word—a word beginning with A, such as ATARI. Type in
the following words, switching between upper- and lowercase letters
with the I Caps | key:

ATARI 130XE atari 130xe

The numbers appear the same whether you are typing capitals or
lowercase letters. Unlike a typewriter, the computer has separate keys
to control capitalizing and shifting. In both the lowercase and the
uppercase modes, the symbol that appears is always the one shown
on the bottom of a key. To get the symbol on the top half of a key, use
the I Shift l key. There are two I Shift I keys on the keyboard. You can use
either one.

Using the I Caps | . 1 Shift l, and PD keys, try typing this:

■ ! ! ATARI 130XE ! ! ! ! ! ! atari 130xe ! ■ I

Experiment with different words, letters, and punctuation marks.

GRAPHIC SYMBOLS

Many of the keys have two or three symbols on them. Each letter key
has a letter on the top side and a graphic symbol on the front side.
Some of the other keys have three symbols or words, all on the top
side. One function o f a key is activated by pressing the key only,
another by pressing I Shift I and the key, and the third by pressing
I Control | and the key. Graphic symbols are produced by pressing
I Control I and the key.

To type a graphic symbol (the symbol on the front side of a letter key),
use the I Control I key on the left side of the keyboa rd. First press the
I Control | key. While you are still holding down the I Control | key, press a
graphic symbol key. Then release both keys.

Hold down the I Control | key and try typing ATARI. You should see this:

Only five characters appear on the screen. If you use the I Control | key
when you press a number key, no graphic symbols appear.

Graphic symbols are most useful in making screen designs, borders,
and simple artwork. You can lock the keyboard into graphic symbols
by holding down I Control | and then pressing I Caps I . Pressing I Caps | just
once will put you back into the lowercase mode.

CURSOR CONTROL

The | Control | key is used most frequently for directing the movement of
the cursor. The cursor is the small white square that marks your place
on the screen. Find the Up Arrow key[“j] next to the letter P. The
arrow, like the I Control I key, is outlined in white. This white marking
indicates that the arrow function is activated only by using the I Control I
key. Press the I Control | key and then the Up Arrow key [?j] and watch
the cursor move up to the top of the screen. When it reaches the top,
the cursor returns to the bottom of the screen and starts moving up
again. Now try out the other directional arrow keys: [T 7 ;, if 7 ], [°~ 7 |.
Remember to use the I Control I key. ~

CLEARING THE SCREEN

The I Control | key is frequently used in conjunction with the I Clear I key
to erase everyt hing o n the screen. Press and hold the I Control I key,
then press the 1 Clear | key. This action should clear your screen and
return the cursor to the upper left-hand corner of the screen. Try it
again.

Now fill up the screen with more letters, numbers, words, and graphic
symbols. This time use the I shift I key with the I Clear I key to clear the
screen. Both I shift | | Clear | and I Control 11 Clear I empty the screen and
return the cursor to the upper left-hand corner.

INSERTING

The I Control | key is used with the I insert | key to insert spaces in a line.
To practice this function, type

■ ! ■ ATARI 130KE ■ ■ ■

Position the cursor on top of the first letter A in ATARI. Holding down
the [Control | key, press the I insert | key 11 times. You should see this:

! ! ! ATARI 130KE ■ ! !

Eleven blank spaces have been added in the middle of the line. This
function is very useful for inserting words. Using the cursor control
keys (the arrows), return to the space next to the third exclamation
mark on the line. Press the space bar once and type THIS IS AN in the
blank spaces as shown below:

! ! ! THIS IS AN ATARI 130HE ■ ! !

To add blank lines, rather than individual blank spaces, hold down the
I Shut | key, then press the I insert l key. A whole new blank line will
appear on the screen. Insert a few more blank lines, but don’t insert
so many that you have a blank screen. Keep the sentence on the
screen so that you can proceed to the next exercise.

DELETING

Using the I Control I key with the I Delete Bk Sp] key makes deleting just
as easy as inserting. Position the cursor on the T in the word THIS.
Holding down the I control I key, press the I Delete Bk Sp] key 11 times.
Your screen should look like this:

! ! ! ATARI 130XE ! ! !

You now know how the i control I and I Delete Bk Sp I keys work. To
discover what the I Delete Bk SpI key does w hen pressed by itself, posi¬
tion the cursor on the first A and press the I Delete Bk SpI key three
times. Your screen should look like this:

ATARI 130XE ! ! !

When used alone, the I Delete Bk SpI key moves the cursor to th e left,
erasing as it goes, but it does not close up the space. Using the 1 Control |
key with the I Delete Bk Sp I key erases the characters to the right and
closes up the gap.

The third function of the I Delete Bk SpI key requires t he use of th e I Shift J
key. Pressing and holding I Shift 1 and then pressing | Delete Bk s ^j
deletes an entire line and returns the cursor to the left margin. It does
not matter where the cursor is positioned on the line when you press
I Shift! I Delete Bk SpI : the entire line is erased from the screen.

TABS

On a blank screen move the cursor to the left margin and type an
asterisk. Press the I Tab I key. Every time the cursor stops, type an
asterisk. You should have six asterisks spaced across the screen as
shown below:

* * *■ * * *

Press the iTabi key only and notice that it stops at the same preset
tab marks every time. The first preset tab is five spaces from the left
margin (a normal paragraph indention), and the following tabs are
eight spaces apart. Position the cursor on top of the first asterisk and
move it in three spaces. Press and hold I Shut | and then press ITabi to
activate the 1 Set Tab | function. Move the cursor back to the left margin,
then press the ITabi key. The cursor jumps to the newly set tab position.

Continue to press the I Tab 1 key. It continues to go to all the preset tab
positions, in addition to the new one. When the cursor jumps down to
the next line, it ignores the new tab position. (But on all the following
lines the cursor will go to all the tab positions—the new one and the
preset ones.) Return the cursor to the first asterisk and press the
ITabi key. The new tab mark is still there.

Return the cursor to the left margin. Press ITabi to move it to the first
tab mark (three spaces in). Use the I control I key with the ITabi key to
activate the icir Tab I function. Press the ITabi key to get to the next
tab position and clear that one also. Move the cursor back to the left
margin of the same line and press the ITabi key only. The cursor
should skip two tab positions. Continue pressing the [Tab key until the
cursor drops to the next line, icir Tab I did not clear the second tab
position on this line. (However, both tab positions have been cleared
from all the following lines.)

INVERSE VIDEO

Type the word ATARI. Find the Inverse Video key H and press it just
once. Type ATARI again. Press the Inverse Video key again and type
ATARI again. Your screen should look like this:

ATARI HHlH ATARI

Inverse Video creates blue letters on a white background, the inverse
of the normal screen colors. This function is very useful for
highlighting letters in your programs. Just one touch of the Inverse
Video key changes the way the letters are displayed.

MISCELLANEOUS KEYS

Another important key is the Escape key I Esc | . When you press it
once, nothing happens. When you press it twice or more, this graphic
appears on the screen: t • Press I Return | and try again. In later sec¬
tions you will need to use the I Esc | key.

The I Break I key is in the upper right-hand corner. When you press this
key, the cursor drops one line and moves to the left margin. In the
chapter about looping, you will learn how to use the [BreakJ key.

When you press the I Heipj , | start I I Select I . and I Option! keys, nothing
happens. These keys are programmable and often have functions in
software programs.

After you press the I Reset I key, the screen will turn bl ank for a second
or two, and the Ready prompt will appear. The 1 Reset I key restarts the
system. You should use this key very sparingly because, in many pro¬
grams, the information that you are entering or have entered will be lost.

Writing a

Simple BASIC Program:

new, list, print, run

Once you know your way around the computer keyboard, it’s easy to
write your first program. To begin, clear the screen and make sure the
cursor is on the left-hand margin.

NEW: CLEARING THE COMPUTER’S MEMORY

Type in the word NEW, then press |Return| :

NEM

NEW tells the computer to get ready for a new set of instructions by
erasing any old instructions that might be in the computer’s memory.

LIST: CHECKING THE COMPUTER’S MEMORY

To make sure nothing is in the computer’s memory, ask the computer
to list any instructions that it might be storing. Type LIST on a line by
itself and press I Returnl :

LIST

If you typed NEW correctly, nothing other than the Ready prompt ap¬
pears on your screen. Now you can begin a new program. Type in the
first line of instruction to the computer. Type in the line exactly as it
appears below and press I Return! after the last quotation mark:

18 PRINT "I HEARD OF A POET NAMED SAM"

All instruction lines in BASIC programs are numbered. When you type
this one-line program, make sure that the 1 and the 0 in the number
10 are numerals, not letters. If you used letters instead of numbers,
you will get an Error message.

A numbered instruction line in a program can be longer than one line
on the screen. When the cursor runs out of space on one line, it
automatically drops down to the next line. You should press [Returnl
only at the end of an instruction line to tell the computer that you are
done typing the instruction and that it should store the instruction in its
memory. Nothing dramatic happens when you press I Returnl ; the
cursor merely returns to the left margin so that you can begin another
line in the program.

RUN: EXECUTING INSTRUCTIONS

To make the computer execute your program, you have to type RUN.
The RUN command tells the computer to carry out its instructions.

Type RUN and press fReturnl to see what happens:

RUN

I HEARD OF A POET NAMED SAM

The computer’s first and only instruction, line 10, was to print the
words inside the quotation marks. Clear the screen, type RUN again,
and press iReturnl . The computer follows its instruction again and
prints I HEARD OF A POET NAMED SAM.

Even though the instruction is no longer on the screen, the computer
remembers what to do. Your program is stored in RAM (Random
Access Memory), the programmable section of the computer’s
memory. When you type LIST, the computer shows on the screen all
the instructions stored in the RAM portion of its memory. Type LIST.
Your screen should look like this:

LIST

10 PRINT "I HEARD OF A POET NAMED SAM"

If your screen looks different, you might have forgotten to press
IReturnl at the end of each entry or to type LIST on a line by itself.

Type in the line below, then give the RUN command:

20 PRINT "I MET HIM ONE DAY, AND TO MY DISMAY, "

RUN

The words enclosed in the quotation marks in both lines of the pro¬
gram appear on the screen. Type LIST to see the instructions that the
computer has stored in RAM. Both lines 10 and 20 appear.

LINE NUMBERING: CREATING ORDER

Each instruction line in a BASIC program must have a number in front
of it. The numbers are called “line numbers.” The computer executes
the instructions, beginning with the smallest number and continuing
through the program until all the instructions have been carried out.
The usual procedure is to number lines by tens so that enough
numbers are available for inserting additional lines later, if desired. Try
inserting a line now. Add line 15 (shown on the next page) and instruct
the computer to run the program. Your screen should look like the
following:

15 PRINT "WHOSE POEMS WERE THE TALK OF THE LAND . "

RUN

I HEARD OF A POET NAMED SAM

WHOSE POEMS WERE THE TALK OF THE LAND.

I MET HIM ONE DAY, AND TO MY DISMAY,

The computer automatically inserted line 15 between lines 10 and 20.
Write another line:

30 PRINT "HIS BRAINS MERE SILICON-SAND . "

RUN

LIST

The RUN and LIST commands cause all four lines of PRINT instruc¬
tions to appear on the screen.

ERROR MESSAGE: COMPUTER TALK FOR
“I DON’T UNDERSTAND”

PRINT simply tells the computer to print whatever is inside quotation
marks on the screen. The computer doesn’t care what words or symbols
are inside the quotation marks; the words don’t need to be spelled cor¬
rectly or make sense. Try out the instructions below:

48 PRINT "AYE SAY HYE; U SAY BI. "

RUN

Even when the quotation marks enclose a nonsense sentence containing
misspelled words, the computer does what it is told to do. However,
try misspelling PRINT as shown below and see what happens:

50 PRIMT "I SAY HI; YOU SAY BYE. "

The computer sends you an Error message. The computer checks up
on only those instructions that are outside the quotation marks
because those instructions are intended for the computer. Instructions
that are inside the quotation marks are intended for you, so the com¬
puter copies them exactly. Move to a blank line but do not clear the
screen. Run the program to see what happens.

Error message 17 appears at line 50, the line in which you intentionally
misspelled PRINT. Error message 17 is called the “syntax error." It
indicates that the instructions were undecipherable to the computer.
(For a complete listing of Error messages, see Appendix D.)

There are several ways to correct an Error message. The easiest solu¬
tion is to move the cursor to the line that contains the typing error.
Place the cursor on the offending M in PRIMT and change it to N.

Press iRetuml . (In this case, you can press iReturnl regardless of the
cursor’s position on the line, even if it is in the middle of the word
PRINT,) No new Error message appears this time. Clear the screen
and run the program. The screen should not show any Error
messages.

Another way to correct an Error message is to erase the offending
line, To practice this technique, type another line that has an inten¬
tional error. This time omit the quotation marks in the PRINT state¬
ment below, then run and list the program:

68 PRINT I ONCE HAD A PROGRAM CALLED BOZON

RUN

LIST

An Error message appears when you press IRetuml and when you try
to run and list the program. To erase the offending line, simply type
the line number and press IReturnl :

RUN

LIST

Now the program runs and lists without errors, although line 60 does
not contain any instructions. The line I ONCE HAD A PROGRAM CALLED
BOZON has been erased. Typing the line number and pressing IRetuml
erases a line entirely from the computer’s memory. Type the line cor¬
rectly as shown below:

60 PRINT "I ONCE HAD A PROGRAM CALLED BOZON"

RUN

PRINT: CREATING BLANK LINES

Inserting a blank line after the poem would make the poem more
readable. Type in the following instructions to create a blank line
between lines 30 and 40:

35 PRINT

RUN

LIST

When nothing follows the PRINT command, the computer creates a
blank line. Insert another blank line between lines 50 and 60. Use 55
for the line number and type only the word PRINT after it.

? : ABBREVIATION FOR PRINT

You can save time and effort by substituting a question mark (?) for
PRINT. Try the next program line below:

78 ? "THAT RAN FROM DUSK UNTIL DAMN. "

RUN

LIST

The program runs the same with ? as with PRINT. The question mark
is just a convenient shortcut. For clarity, all the following PRINT
statements in this tutorial use the word PRINT, but you can substitute
a question mark.

LOGICAL LINE LENGTH

Sometimes the quotation marks contain too many characters to fit on
one or two lines. Make sure the sound is audible on your television or
monitor before you type the following sample:

80 PRINT "IT MOULDN'T RESPOND TO ESCAPE, BREAK.. CONTROL,
OR LIST, AND IT MAS STILL RUNNING MHEN I TURNED OFF THE
SNITCH."

When the cursor reaches the third line, a buzzer sounds. The buzzer
indicates when you are approaching the maximum length of an in¬
struction line. An instruction line can be no longer than three screen
lines. This limit is called a “logical line.” (You may wish to turn down
the volume now.)

SCREEN DISPLAY

Words are often broken in awkward places when the cursor reaches
the end of a line on the screen. Also, the spacing between words
when you type in the program lines is different from the word spacing
when the computer runs out the program. To avoid both of these prob¬
lems, determine what you want each line to look like and type
separate PRINT statements for each line. Retype the sentence in line
80 so that it appears in a poem format:

80 PRINT "IT MOULDN'T RESPOND"

90 PRINT "TO ESCAPE, BREAK, CONTROL, OR LIST,"

100 PRINT "AND IT MAS STILL RUNNING"

110 PRINT "MHEN I TURNED OFF THE SMITCH . "

RUN

LIST

PRINTING GRAPHIC SYMBOLS

You can also use graphic symbols in PRINT statements to produce
simple artwork. To set off the poem, type the lines below. Use | Control I
in and .Control! HT to create the graphics:

58 PRINT
115 PRINT

PRINT 11 IS ": CLEARING THE SCREEN

You can make your program look even better by making sure the
screen is clear when you start. Type a line number, PRINT, and the
first quotation mark. Press the I Esc I key once lightly. Then press either
the I shift I and I Clear I keys or the I Control I and I Clear I keys. A bent
arrow appears on the screen. Type another quotation mark and press
IRetumj . Then run and list the program:

5 PRINT " IS"

RUN

LIST

Control | 0: STOPPING THE SCREEN DISPLAY

Now the program looks better, but it is too long for all the lines to
appear together on the screen. When the computer lists the program,
you can stop the lines as they move up and off the screen by pressing
the |Control| and the □ keys. Type LIST. Use two fingers on your left
hand to press the I Control I and j] keys and one finger on your right
hand to press |Return| . | Control | [T both starts and stops the LIST
function.

Creating an Interactive Loop:

GOTO, DIM, INPUT

Loops tell the computer to go back and repeat instructions in the
program automatically. The GOTO command saves you the trouble of
typing the same instruction lines over and over again. The DIM and
INPUT commands allow you to interact with your computer on a
question-and-answer basis. Putting these three commands together—
GOTO, DIM, INPUT—lets you have an ongoing conversation with your
computer.

GOTO: A COMPUTER’S MAP

The simplest computer loop is the GOTO loop. GOTO is always
followed by a line number that tells the computer where to go on the
next command. You need just two commands to create a loop. Type in
the program below to produce an infinite loop:

NEW

lie PRINT "CONGRATULATIONS!"

120 GOTO 110
RUN

To break this infinite loop, turn off the machine or use the FBreaH key.
When you stop the loop with the FBreakl key, one of the following
messages appears:

STOPPED AT LINE 110

STOPPED AT LINE 120

The computer is telling you where it was when it received the
command to stop.

Comma: A Tab Maker

The GOTO loop puts out an endless amount of work with just two lines
of instruction. To make the program fancier, list your program, position
the cursor in the space next to the last quotation mark, insert a
comma, and press 1 R eturnl . Run the program and watch the special
effects:

LIST

lie PRINT "CONGRATULATIONS! ",

120 GOTO 110
RUN

The comma acts like a tab. Each time the computer moves down to
the next line and prints CONGRATULATIONS!, it moves to the next tab
position. The result is a barber-pole effect. Remember to break the
loop with the I Break I key.

Semicolon: Computer Glue

A semicolon produces another kind of effect. List the program, change
the comma in line 110 to a semicolon, press |Retum| , and run the
program:

LIST

110 PRINT CONGRATULATIONS! 11 .:

120 GOTO 110
RUN

The semicolon glues the PRINT statements together with no space in
between. To put some space between the words, go back and edit line
110 so that it looks like this:

110 PRINT "CONGRATULATIONS!

RUN

Colon: A Separator

The colon is a separator. It permits two instructions to be placed on
one line. Change the semicolon in line 110 to a colon and add the
PRINT statement below:

lie PRINT "CONGRATULATIONS! 11 : PRINT "YOU JUST MON THE
LOTTERY."

RUN

As you progress in your programming ability, conserving space in the
computer’s memory becomes important. Consolidating commands on
one line with a colon is one way to help save free bytes of RAM
memory. (A byte is one character of information.) To see how much
memory is conserved, type the following statement:

PRINT FRE C05

The computer will answer with a number. Reprogram line 110 so that
the two PRINT statements take up two program lines:

lie PRINT "CONGRATULATIONS!"

115 PRINT "YOU JUST HON THE LOTTERY . "

PRINT FRE CO)

Compare the two numbers of free bytes available. The second number
is two or three less than the first. Because simplicity is more
important to a beginning programmer than conservation of computer
memory, the program lines in this section will usually contain only one
statement per line. One exception will be a PRINT statement that
inserts a blank line between segments of the program. Type in the
new line below to see the effect:

lie PRINT:PRINT "CONGRATULATIONS!"

RUN

DIM AND INPUT: DIMENSIONING AND INPUTTING
STRING VARIABLES

The computer must be programmed to respond to a question. You can
use a PRINT command to ask a question and an INPUT command to
enter a response into the computer. However, when you give the
computer an answer, the computer must know where to put it. It
places it in a spot called a "variable” in RAM memory. If the answer
is composed of letters, numbers, or both, it is called a "string
variable." Your ATARI 130XE Computer needs to know how much
space you will need for an answer so that it can reserve space for it.
This process is called “dimensioning the string variable."

The DIM (dimensioning) command always accompanies the INPUT
command for string variables because DIM determines the expected
size of the answers. For variables, the size refers to the number of
characters, including blanks, that are needed. You have to tell the
computer the maximum number of spaces that the answer can
occupy.

Change the loop program to a program that asks a question and
expects an answer. There is no need to rewrite the program; just write
in the new lines—lines 10, 120, 130, and 140—as shown below.
(Typing in the new line 120 automatically erases the old line 120.)

18 DIM ANSWERS CIOOI

110 PRINT: PRINT "CONGRATULATIONS!"

115 PRINT "YOU JUST MON THE LOTTERY . "

120 PRINT : PRINT "HOW DOES THAT MAKE YOU FEEL?"

130 INPUT ANSWERS

140 PRINT "I THOUGHT YOU WOULD SAY THAT. "

RUN

Line 10 tells the computer to save enough space in its memory for an
answer that is a maximum of 100 characters. The variable in this
program has been named ANSWER. The variable is going to store
letters and numbers, so it is a string variable. String variables are
designated by a dollar sign after the last letter of the variable name.

Line 130 allows you to enter an answer. When you run the program,
the computer displays the question on the screen, and you then type
in your answer. That answer is stored in the string variable called
ANSWERS. If the DIM statement, line 10, was omitted, an Error
message would occur, and the INPUT statement wouldn’t work.

?: Courtesy of INPUT

Run the program again. Two question marks will appear on the
screen. The second question mark will be on the line next to the left
margin. List your program and notice that you typed only one question
mark in the program. The INPUT command always puts a question
mark on the screen for you. Type the variation of line 120 below:

Run the program and type in your response when the computer asks
its question. Now only one question mark appears, and your answer
immediately follows the question on the same line. Create some more
dialogue by dimensioning more string variables and inserting more IN¬
PUT statements. The DIM statements should be at the beginning of
the program:

20 DIM DATES C25J

140 PRINT : PRINT "HHEN MOULD YOU LIKE TO COME AND PICK UP
YOUR PRIZE" j
150 INPUT DATES
RUN

String Variables in PRINT Statements

The computer program now asks two questions but doesn’t respond to
your last answer. To get a response, you can place the string variable
in the PRINT statement in the following way:

160 PRINT "I * M SORRY, BUT OUR OFFICES ARE ALMAYS CLOSED
ON "JDATES;" . TOO BAD! "

The semicolon glues the string variable between two phrases in
quotation marks. Run the program. If the words are not spaced
correctly, compare your line to the line above. You probably left out a

space after the N of ON or forgot the period and the space before
TOO BAD!. Those spaces are important. Practice with another string
variable input:

38 DIM HOMES tl)

170 PRINT "BY THE MAY,. WHAT IS YOUR NAME" ;

180 INPUT NAMES

ISO PRINT "HELL.. " ; NAMES; " f I BET YOU MOULD LIKE TO KNOM
HOH MUCH YOU HON . FIRST YOU HAVE TO ANSHER A QUESTION. "

Run the program. Even though you typed in a full name, the computer
printed only the first initial. That happened because the area
dimensioned in RAM memory for the name was too small. Most
people’s names are longer than one character. Change line 30 to a
more reasonable number of spaces and run the program:

30 DIM NAMES C25J
RUN

Inputting Numeric Variables

So far you have been working with alphanumeric string variables—
variables composed of letters, numbers, or both. For instance, the
computer would accept the name R2-D2 or 007 as a string variable.
Flowever, the number name would be used only as a name, not as a
number in any math problems. Now try some numeric variables that
can be used in mathematical calculations. Numeric variables do not
need a DIM command or a dollar sign. Enter the following program
lines:

200 PRINT : PRINT "HOH OLD ARE YOU";

210 INPUT AGE

220 PRIZE=AGE*1000

230 PRINT : PRINT 11 YOU HAVE JUST HON $" ; PRIZE; " FROM THE
LOTTERY. YOU CAN COLLECT DURING OFFICE HOURS. 11

In this program, the age that you enter is stored in the numeric
variable called AGE. Line 220 creates another variable called PRIZE.
Line 220 allows the computer’s built-in calculator to calculate the
prize money, which is $1000 multiplied by the age of the winner. (To
the computer, * means multiply.) The program does the math for you
and stores the answer in PRIZE. Line 230, which places the numeric
value inside the PRINT statement in the same manner as string
variables, tells you what the answer is.

INPUT LOOPS

To repeat your conversation with the computer, add a loop command
to the program again. A GOTO statement at the end will make the
computer repeat the program from the beginning. For program
readability, use a REM statement to show where the main
conversation portion of the program begins. A REM (remark) statement
functions like a label for the programmer. The computer does not
carry out REM commands but only prints them when you list your
program.

100 REM *** CONVERSATION LOOP ***

240 GOTO 100

The computer must return to line 100, rather than line 10, because it
cannot go back over the DIM statements for string variables. If it loops
over the same DIM statements, you will receive an Error message.

Using Random Numbers
and Mathematical Functions:

RND, *,/

Initially computers were developed to process numbers quickly and easily.
To take advantage of the computer’s ability to calculate a math answer
in a few milliseconds, you must know how to speak to a computer.

NUMBERS

Type the statement below and press iReturni :

PRINT 10

The computer should print the number 10. Make sure you use the
numerals 1 and 0, not letters. Practice printing the following numbers:

PRINT 1000000000
PRINT-100000000

Use the minus sign (-) on the Up Arrow key jfj to indicate negative
numbers. Do not use commas in numbers. Type the statements below
to see what happens when commas are used:

PRINT 9/876/543/210
PRINT 9/ 876/ 543/ 210

In both examples, the computer interprets the commas as separators
in a series of numbers. It spaces the numbers out across the screen
according to its preset tab positions. To the computer, the 9 is not 9
billion, just the number 9 followed by a series of other numbers.

SCIENTIFIC NOTATION

The computer may not understand commas when it prints numbers,
but it does understand exponents. Often it will automatically translate
a large number into an exponential form. Try the numbers below:

PRINT 33333333333
PRINT 55555555555
PRINT 11111111111
PRINT-11111111111
PRINT-98765432112

These numbers are large or small enough that the computer prefers to
rewrite them in scientific notation. Familiarity with scientific notation is
not essential for understanding the computer, or even this chapter.

Scientific notation expresses a large number as a number between 0
and 10 multiplied by a power of 10. An exponent specifies the power
of 10. In the following example, E + 13 means that the exponent is 13

2.5E + 13 = 2.5 X 10 13 = 25000000000008

You can use exponents to talk to your computer. The caret on the
Right Arrow key is the symbol for exponents. You must use the
1 shift | key to print the caret. Try the following computations:

PRINT 2 a 1
PRINT 2 a 2
PRINT 2 a 3
PRINT 2 a 4
PRINT 2 a 64

The first notation is 2 to the first power; the second, 2 to the second
power; and so on. The last notation is 2 to the sixty-fourth power,
which is a large enough number that the computer needs to express
it in scientific notation.

Unless you are a physicist timing electrons in their orbits or an
astronomer calculating the size of the universe, you will rarely need to
use scientific notation. But if you ever do, the computer is capable of
doing your calculations with even these often unwieldy numbers.

THE COMPUTER AS A CALCULATOR

The computer can perform the same fun ct ions as a calculator. Use
the plus (+) sign on the Left Arrow key |c ? '] to type the statement
below:

PRINT 1 + 1

When you press I Return 1 , the computer immediately gives you an
answer, just like a calculator. Invent your own addition problems now.
Make the numbers big or small, and try a long series of numbers to
add up. Experiment with lots of variations.

Use the minus sign (-) on the Up Arrow key “_] for subtraction prob¬
lems. Try the three versions of the same problem below:

PRINT 4-1
PRINT 4-1
PRINT4—1

The same answer appears for each example as soon as you press
|.Return The spacing in math problems is unimportant to the com¬
puter. Try out problems of your own. Make long problems that com¬
bine subtraction and addition functions.

The multiplication sign—the asterisk (*)—is located on the Right
Arrow key [SJ . The division sign is the slash (/) on the Question Mark
key Type the following statements:

PRINT 2 * 2
PRINT C2*2>

PRINT 6/3
PRINT C6/3J

The computer not only understands the use of parentheses in math
problems but needs them when the problems become complex. Notice
what happens in this problem with and without parentheses:

PRINT 3* £2 + 2 J
PRINT 3*2 + 2

The answer to the first problem is 12; the answer to the second prob¬
lem is 8. In the first problem, the computer first adds 2 and 2, then
multiplies by 3 to arrive at 12. In the second problem, the computer
multiplies 3 and 2 first, then adds 2 to arrive at 8. Whenever the com¬
puter encounters parentheses in a math problem, it does the computa¬
tions inside the parentheses first and then finishes the rest of the
calculations.

Try out the problems below to discover some other interesting facts
about how your computer works. See if you can predict the answers
before you press | Return I

PRINT C2+2J*3
PRINT 2 + 2*3

In the first problem, the computer does the computation inside the
parentheses first. In the second problem, the computer does the
multiplication first, then the addition. The computer executes these
mathematical functions according to rules of order: first, computations
inside parentheses; second, exponential functions; third, multiplication
and division functions as they appear in the problem from left to right;
and last, addition and subtraction functions from left to right. The rules
are summarized in the following table:

Order of Mathematical Execution

1. ( ) Computations

in parentheses

2. A Exponential

functions

3. * Multiplication

/ Division

4. + Addition

Subtraction

In order of appearance
from left to right
In order of appearance
from left to right

RANDOM NUMBERS

The computer can perform other functions that your calculator most
likely cannot do. For example, your computer can pick random
numbers for you. Type the program below:

NEM

18 PRINT RND (0J
20 GOTO 10
RUN

RND is the command for generating random numbers. The infinite
loop in the program above will generate random numbers endlessly.
Remember to break the loop with the I Break I key. To make changes in
the program, you can just list the program and use the cursor keys to
insert characters, rather than retype entire.lines. Try out the various
programs below:

10 PRINT RND (11
RUN

10 PRINT RND (1233
RUN

10 PRINT RND (503
RUN

10 PRINT RND (500003
RUN

All four variations of line 10 generate random numbers between 0 and
1. The decimal point is always before the first digit in a random number.
The few random numbers that have a number on the left side of the
decimal point are still between 0 and 1 but are so small that the com¬
puter has written them in scientific notation.

The number in the parentheses is called a “dummy variable.’’ It does
not matter what number is used as the dummy variable, but it is im¬
portant that the parentheses appear and that they enclose something
(any number or letter). For typing ease, 0 is usually placed in the
dummy variable position. Change line 10 again as shown below:

10 PRINT CRNDC0) * 10)

RUN

10 PRINT CRNDC0) * 100}

RUN

10 PRINT CRNDCO) * 1000)

RUN

Each program generates a different range of random numbers. PRINT
(RND(O) * 10) generates numbers up to 10 because the statement in¬
structs the computer to multiply the random number by 10. Multiplying
by 10 moves the decimal point over one place. In PRINT (RND(0) *
100), multiplying by 100 moves the decimal point over two places, and
in PRINT (RND(0) * 1000), multiplying by 1000 moves the decimal
point over three places. If you want, you can multiply by much larger
numbers to generate large random numbers.

Because long numbers with many digits after the decimal point are
cumbersome, the computer has an instruction that tells it to print only
integers. Integers are whole numbers without any decimal points. The
instruction I NT tells the computer to drop everything after the decimal
point. Reprogram the three variations of line 10 above and compare
the results:

10 PRINT INTCRNDC0)M10)

RUN

10 PRINT INTCRNDC0)*100)

RUN

10 PRINT INTCRNDC0)*1000)

RUN

The programs generate numbers in the same ranges as before, but
the numbers are more readable without the digits after the decimal.

To generate numbers in a more specific range, try the examples
below:

10 PRINT INT CRNDC0)*3)

RUN

10 PRINT INT CRNDC0)M12)

RUN

10 PRINT INT CRNDC0)*25)

RUN

The program generates random numbers that are always one less
than the number by which they are multiplied. The first line 10
generates the numbers 0, 1, and 2. To generate random numbers 0, 1,
2, and 3, the program would be written this way:

10 PRINTINT (RNDC0)*4J
RUN

To generate only the numbers 1, 2, and 3, the program should look
like this:

10 PRINT INT CRNDC0)*3)+1
RUN

To generate three numbers starting at 20, write the program this way:

10 PRINT INT CRNDC0)*3)+20
RUN

Random Number Game

Random-number programs are very flexible. You can even use them to
play games with your computer. Type the following program.
Remember that to get the bent arrow in line 5, press I Esc I . hold down
| Shift | or I Control | , and press I Clear I .

NEM

1 REM *** NUMBER . GAM ***

5 PRINT " ^ "

10 SECRETNUM=INTCRNDC0)*3)+1

20 PRINT : PRINT "I AM THINKING OF A NUMBER, EITHER 1,2,
OR 3 . TRY TO GUESS IT. "

30 INPUT GUESS

40 IF GUESS=SECRETNUM THEN PRINT "YOU HON. "

50 IF GUESSOSECRETNUM THEN PRINT "YOU LOST. "

50 GOTO 10

Line 10 assigns the random number to the numeric variable called
SECRETNUM. Line 30 lets the user type in a guess and assigns this
number to the numeric variable called GUESS. (Remember that
numeric variables do not need to be dimensioned or tagged at the end
the way that string variables do.) Line 40 compares the guess to the
secret number. If they equal each other, the computer prints “YOU
WON." Line 50 also compares the guess to the secret number. If they
are not equal (the symbols < > mean not equal to), the computer prints
"YOU LOST." Line 60 makes a loop so that you can play the game
again. (The next chapter explains IF-THEN statements in more detail.)

MATH PROGRAMS

The computer's mathematical functions can be used for work pur¬
poses, as well as for play. If you were a chef who prepared food for
banquets, you might need a computer to expand your recipes. For
instance, suppose that you are trying to figure out how many pounds
of sea scallops to buy to serve Coquilles St. Jacques at a dinner for 62
guests. Your recipe indicates that 1 1/2 pounds of scallops feeds 5
people. The program below would tell you how many pounds to buy:

NEH

1 REM *** COQUILLE ***

16 PRINT " Fi 11
26 GUESTS=62

36 P0UND3T0BUY= 1.5/5 * GUESTS

40 PRINT:PRINT "BUY ";POUNDSTOBUY;" POUNDS OF
SCALLOPS. 11
50 END

The program produces the answer (18.6 pounds of scallops), but a
calculator would achieve the same result with less work To make the
program more useful, allow a variation in the number of guests by in¬
serting an INPUT statement. Type in the additional lines below:

15 PRINT: PRINT "HOMMANY GUESTS DO YOU EHPECT?"

20 INPUT GUESTS

Run the program several times, entering a different number of guests
each time. The amount of scallops needed changes each time. For
200 guests, 60 pounds of scallops are required; for 436 guests, 130.8
pounds. The INPUT function makes the program more practical.

Making Decisions
and Solving Problems:

^ IF-THEN, FOR-NEXT

The IF-THEN and FOR-NEXT commands enable you to write programs
that mimic the way humans approach a decision or a problem.
Especially useful for games and logic puzzles, the commands let you,
the programmer, make the choices for the computer.

IF-THEN COMMANDS

To practice the IF-THEN statement, type in the following program:

NEW

1 BEM *** BRNPROBE . QZ ***

5 PHIMT " H "

IB DIM RAIN$ (31

20 PRINT : PRINT "YES OR NO, IF IT MERE RAINING OUTSIDE,
MOULD YOU GO OUT HITH AN UMBRELLA";

30 INPUT RAINS

40 IF RAIN$="YES" THEN PRINT "YOU HAVE A FORMIDABLE IQ . "
50 IF RAIN$="NO" THEN PRINT "YOU ARE A BORN RISK TAKER. "

The Brainprobe Quiz evaluates your answer. In line 40, if the answer
stored in the string variable RAIN$ is yes, the computer prints the IQ
message. If the answer is not yes, the computer reads the next line,
line 50, and evaluates the string variable RAINS again. If the answer is
NO, the computer prints the risk-taker message. However, if you
answer neither yes nor no, the program just ends. The program has no
instructions for responding to an indefinite answer. Try it out.

One way to encourage an expected reply is to create an infinite loop.
Insert the additional line below:

60 GOTO 20

Evaluating with IF-THEN

Another way to encourage a correct answer is to provide hints. The
following program uses numeric variables to elicit a correct response:

NEH

1 REM *** NUMBER . QZ ***

5 PRINT " H 11

10 SECRETNUM=INT(RND(01*101+1

20 PRINT : PRINT "GUESS A SECRET NUMBER BETHEEN 1 AND 10. 11

38 PRINT

40 PRINT "YOUR GUESS";

50 INPUT GUESS
60 PRINT

70 IF GUESS=SECRETNUM THEN PRINT "YOU GOT IT ! " : END
80 IF GUESS<SECRETNUM THEN PRINT "TOO LON. TRY AGAIN. 11
GOTO 40

90 IF GUESS>SECRETNUM THEN PRINT "TOO HIGH. TRY
AGAIN.":GOTO 40

Lines 80 and 90 evaluate the guess as greater than or less than the
secret number. The PRINT statement provides a hint that the next
guess should be higher or lower. The GOTO commands in lines 80 and
90 create an infinite looo if you continue to guess incorrectly.

Ending the Program

The Number Quiz is programmed to stop only when you discover the
secret number. When you enter the correct answer, line 70 gives the
computer the instruction to end. END stops the program, and the
Ready prompt appears on your screen.

Trapping Errors

If you accidentally enter a letter instead of a number for GUESS, the
computer sends an Error message, and the program ends abruptly.
Make an intentional error by typing a letter key or pressing the | Return J
key only. To avoid ending the program, you can use a TRAP command
to trap the Error message. Add the lines below and run the program
again:

45 TRAP 100

100 PRINT : PRINT "PLEASE ENTER A NUMBER ONLY . "

110 GOTO 30

In line 45, the TRAP command tells the computer not to stop the
program when a mistake is entered and sends the computer to line
100. Line 100 tells the computer to print the directions for correcting
the mistake. Line 110 returns the computer to the place where it left
off. The TRAP statement always comes before the INPUT statement,
and it always contains the number of the line that will resolve the
problem.

Quiz Writing with IF-THEN

A program can easily provide hints when the correct answer is a
number, including a date. The following program uses IF-THEN
statements and the TRAP command to evaluate guesses:

NEN

1 REM *** LOVELACE . QZ ***

5 PRINT "IS"

10 PRINT : PRINT 11 ADA LOVELACE.. DAUGHTER OF THE POET LORD
BYRON ^ MAS MATHEMATICALLY BRILLIANT . 11
20 PRINT

30 PRINT "IN MHAT YEAR DID SHE HRITE HER AMAZINGLY
ACCURATE DESCRIPTION OF THE FUTURE USES OF THE
COMPUTER "}

40 TRAP 200
50 INPUT GUESS

60 IF GUESS=1842 THEN GOTO 100
70 IF GUESS<1842 THEN GOTO 110
80 IF GUESSM842 THEN GOTO 120

100 PRINT: PRINT "CONGRATULATIONS! YOU GUESSED THE YEAR
CORRECTLY.":END

110 PRINT: PRINT "THAT MAS TOO EARLY. TRY AGAIN. " : GOTO 20
120 PRINT: PRINT "THAT MAS TOO LATE. TRY AGAIN. " : GOTO 20
200 PRINT .-PRINT "PLEASE ENTER A NUMBER ONLY. "

210 GOTO 20

in the Lovelace Quiz, the placement of the PRINT messages
associated with the IF-THEN statements is different from their place¬
ment in the Brainprobe Quiz and the Number Quiz. This difference
illustrates that there is often more than one way to achieve the same
results in programming.

Computer Bugs

The TRAP statement makes the Lovelace Quiz more errorproof, but it
still is not perfect. Because the computer evaluates the date as a
number, it will accept 1842.78 as incorrect but 1842,78 as correct.
Most programs have “bugs," or problems. When you can figure out
the bugs and fix them, you have really learned to program. Every
beginner encounters many bugs and makes many mistakes. To
become a better programmer, study this manual, refer to the ATARI
BASIC Reference Guide , and perhaps have a more experienced
person look over your shoulder occasionally. You will learn how to
identify bugs so that you can avoid similar mistakes in future
programs.

FOR-NEXT LOOP: THE COUNTING LOOP

You are already familiar with the infinite GOTO loop. Another kind of
loop is the FOR-NEXT loop. The FOR-NEXT loop is a counting loop,
which is not infinite. Type NEW and enter the following program:

NEN

18 FOR X=1 TO 4
20 PRINT "POTATO"

30 NEXT X
RUN

POTATO appears on the screen four times. Change line 10 to read like
this:

10 FOR X=1 TO 7

When you run the program this time, the screen shows POTATO seven
times. The computer is looping seven times through lines 10, 20, and
30. FOR tells the computer how many times to loop, and NEXT tells
the computer to go back to the top and start again. NEXT is similar to
GOTO. X is a variable. You can use anything to represent the variable.
Try this name for the variable:

10 FOR NUM=1 TO 7
30 NEXT NUM

When you run the program, there is no difference from the previous
program. Change the variable name again:

10 FOR JKL=1 TO 7
30 NEXT JKL

JKL is a nonsense name for the numeric variable in the FOR-NEXT
loop. Run the program to see that it, too, runs the same as before.

Now add this line:

15 PRINT JKL^

RUN

The PRINT statement in line 15 shows the value of the variable. (Put
the comma in for readability.) Each time the computer repeats the
FOR-NEXT loop, the variable takes on the value of the next number in
the series specified in line 10. The first time, the variable is 1; the
second time, 2; and so on. The last number in the FOR statement
controls the number of times the computer loops through the program.
Change that number in line 10 as shown below:

10 FOR JKL=1 TO 50
RUN

10 FOR JKL=1 TO 200
RUN

10 FOR JKL=1 TO 500
RUN

Starting Point

List the program. The first number in the FOR line is the starting point
for the count, and the last number is the stopping point. Even negative
numbers can be the starting point for the count. Try these variations
for line 10:

10 FOR JKL = 1 TO 5
RUN

10 FOR JKL=0 TO 5
RUN

10 FOR JKL-3 TO 5
RUN

10 FOR JKL=-10 TO 5
RUN

STEP: Counting Incrementally

List the program, delete the PRINT statement in line 20 and the
comma in line 15, and run the program. The computer counts and
prints the numbers very quickly. Use the STEP command to make the
computer count in increments. Try the program below:

10 FOR JKL=0 TO 500 STEP 5
RUN

10 FOR JKL=0 TO 500 STEP 2
RUN

10 FOR JKL=0 TO 500 STEP 100
RUN

10 FOR JKL=0 TO 500 STEP 7
RUN

The computer will obligingly count by any sequence you specify.

Counting Backward

The computer can count backward if you use the STEP -1 command
and the proper sequence of numbers (from larger to smaller) for
starting and stopping the count. For example:

10 FOR JKL=5O0 TO 0 STEP -1
RUN

10 FOR JKL-10 TO 0 STEP -1
RUN

10 FOR JKL=-1 TO -IS STEP -1
RUN

The computer can count backward in increments also:

10 FOR JKL=50O TO O STEP -20
RUN

10 FOR JKL=50O TO O STEP -3
RUN

10 FOR JKL=0 TO -50O STEP -SO
RUN

You can also instruct the computer to start and stop at any number
you desire:

10 FOR JKL=50O TO 300 STEP -10
RUN

10 FOR JKL=25 TO 0 STEP -1
RUN

Now you know how to instruct the computer to count forward and
backward, to count consecutively and incrementally, and to start and
stop at specified numbers.

The FOR-NEXT “Sandwich” Loop

List your program. FOR is on the top line, and NEXT is on the bottom
line. Whatever you want the computer to do is sandwiched in between
Type in the lines below:

10 FOR JKL=i TO 5

20 PRINT 11 AVOCADO"

The computer will carry out any instruction or number of instructions
between the FOR and NEXT statements the specified number of times
Have the computer print other words:

16 PRINT "CHEESE"

17 PRINT "MAYONNAISE"

18 PRINT "MUSTARD"

19 PRINT "TOMATO"

21 PRINT "BACON BITS"

22 PRINT "LETTUCE"

23 PRINT:PRINT
RUN

The computer prints and counts too quickly for anyone to read the
screen clearly. Nonetheless, it prints the PRINT statement exactly five
times as instructed in the FOR-NEXT statement. Other instructions,
such as math computations and INPUT statements, can also be part
of the FOR-NEXT sandwich loop.

Delay Loops

Erase all the PRINT statements so that absolutely nothing is in the
FOR-NEXT sandwich loop, except the FOR and the NEXT statements.
Run the program and see what happens:

18
13
28
21
22
23

LIST

RUN

Nothing happens. Change the number in line 10 and watch carefully
again:

10 FOR JKL = 1 TO 500
RUN

The Ready prompt takes a few seconds to appear. Change line 10
again:

10 FOR JKL=1 TO 5000
RUN

This time the Ready prompt takes considerably longer to appear. The
computer is counting but not printing its calculations. The process is
similar to counting silently to yourself. The time it takes the Ready
prompt to appear on the screen is the time it takes the computer to
count to 5000.

FOR-NEXT loops are excellent devices for keeping the computer from
moving on. In fact, FOR-NEXT loops are used so frequently for this
purpose that they are sometimes called “delay loops,” and the
common variable name is DELAY. Rewrite the FOR-NEXT loop, using
DELAY as the variable name and different numbers in the FOR
statement:

NEH

10 FOR DELAY=1 TO 300

20 NEXT DELAY

LIST

RUN

Sometimes the delay loop is sandwiched on the same program line:

NEH

16 FOR DELAY=1 TO 30O:NEKT DELAY
LIST

RUN

Sample Programs

The programs below use FOR-NEXT loops in a variety of ways. The
first program uses the FOR-NEXT loop as a simple delay loop to leave
the word HI on the screen long enough to be read before line 30
clears the screen:

NEM

1 REM *** DLAYLOOP ***

5 PRINT 11 IS 11
10 PRINT "HI"

20 FOR DELAY=1 TO 800:NEKT DELAY
30 PRINT " IS "

40 PRINT "BYE"

50 FOR DELAY=1 TO 800: NEXT DELAY

The next program uses a numeric variable in the FOR-NEXT loop. It
also uses a TRAP command that refers the computer back to the
previous line, giving no specific message about the error:

NEM

1 REM *** HOHHIGH? ***

10 DIM AS Cl) / HHSC1)

20 PRINT " IS "

30 PRINT : PRINT "HOH HIGH DO YOU HANT TO COUNT " ;

40 TRAP 30
50 INPUT HH

55 HH$=5TR$CHH) : IF HH$="0" THEN GOTO 30
80 FOR COUNT=l TO HH
70 PRINT COUNT
80 NEXT COUNT

80 PRINT : PRINT "PLEASE ANSMER CY/N) . MOULD YOU LIKE TO
COUNT AGAIN" }

100 TRAP 90
110 INPUT A$

120 IF A$ = "Y" THEN GOTO 30

130 IF A$="N" THEN PRINT:PRINT "BYE"SEND
140 GOTO 90

The last program paraphrases an old rock ’n’ roll song and uses
“nested” FOR-NEXT loops. A nested FOR-NEXT loop is a smaller
delay loop inside a larger FOR-NEXT loop. The program also uses OR
to create multiple conditions in the IF-THEN statement:

NEW

1 REM *** CLOCKRCK ***

5 PRINT N ^ "

10 FOR X = 1 TO 9
20 PRINT H;

30 PRINT " O'CLOCK"

40 FOR DELAY=1 TO 5O0:NEXT DEL AY

50 IF X —3 OR X = 6 OR X = 9 THEN PRINT "ROCK ! " : FOR PAUSE=1
TO 500 : NEXT PAUSE
60 NEXT X

70 PRINT:PRINT "WE 1 RE GOING TO ROCK"

80 PRINT "AROUND THE CLOCK"

SO PRINT "TONIGHT! "

Producing Sound and Graphics:

SOUND, SETCOLOR, COLOR

Creating sound and graphics on some computers is very complicated,
but not on the ATARI 130XE. The SOUND command of ATARI BASIC,
combined with some simple programming techniques, is all you need.
Sound and graphics add new dimensions to your BASIC programs—
anything from arcade-game zaps and cracks, musical themes, and
songs to colorful graphic displays.

SOUNDING OFF

Your ATARI 130E can play up to four sounds at one time. The four
sound registers, or voices, are numbered 0, 1,2, and 3. To select the
first voice, you type SOUND 0; for the second, SOUND 1; for the third,
SOUND 2; and for the fourth, SOUND 3.

The SOUND command in ATARI BASIC controls four elements:

voice (0-3)
pitch (0-255)
distortion (0-14)
volume (0-15)

The pitch, or frequency, of the sound is determined by a number from
0 to 255, giving you a total of 256 frequencies from which to choose.
The pitch value is the second number in the SOUND command.
SOUND 1,50 specifies the second voice with a pitch of 50. Make sure
that the volume is turned up on your TV or monitor, then type

SOUND J.^50^0^8

Press 1 Return I . A great explosion, isn’t it? To turn off the sound, you
just turn down the volume on your television, or type either of the
commands below and press | Return I :

END

SOUND l/O/O^O

The purity, or distortion, of the sound is determined by any even
number between 0 and 14. In the SOUND command, the purity of the
sound is the third number. Try this:

SOUND i.,50,,10,8

The number 10 produces a pure tone without distortion. To put in a
little distortion, change the 10 to 06:

SOUND 1,50/06^8

The computer sounds as if it’s ready for takeoff. Type END before the
neighbors start complaining.

The last number in the SOUND command controls the volume. The
number must be between 0 and 15. Number 8 is a good number for
most uses. You risk damaging your TV speaker and your ears if you go
above 12.

To try some four-part harmony, enter the following:

SOUND 0/50/10/8
SOUND 1/100/10/8
SOUND 2/150/10/8
SOUND 3/200/10/8

Type END to stop the chorus.

Sounding Off with Variables

Variables in SOUND commands add versatility to your programs.

Using variables, you can program the computer to change the voice,
pitch, distortion, and volume of sustained sounds. Enter and run the
following program:

NEM

10 REM * SET VARIABLES FOR SOUND VALUES
20 V0ICE=0:PITCH=1O0:T0NE=8:VOL=8
30 SOUND VOICE/PITCH/TONE/VOL
40 GOTO 20
RUN

To stop the sound, press the I Break I key and type END. To sustain a
sound, you need to repeat the SOUND command in the program. Two
common methods are a FOR-NEXT loop or a GOTO loop like the one
in the example above. The following program uses a variable for the
pitch in a FOR-NEXT loop to produce the computer’s entire range of
pitches:

NEW

10 REM * SOUND EFFECTS WITH FOR-NEKT LOOP

28 UOICE = 0:PITCH=0:TONE=10:U0L=8

30 FOR PITCH = 0 TO 255

40 SOUND VOICE^PITCH^TONE^ VOL

50 NEHT PITCH

RUN

Varying the volume in a program produces a variety of sounds. Change
VOL = 8 to VOL = 0 and press I Return I . Then add the following line:

35 VOL=INTCRNDC0)«16)

This line randomly selects a value between 0 and 15 for the volume
variable. Run the program to find out how randomly changing the
volume affects the sound.

Making Music

The SOUND command can produce musical tones as well. The follow¬
ing scale includes musical notes and their pitch values:

Note Pitch

high C 29

108

121

middle c

Type and run the following program:

NEW

10 REM ** SIMPLE SONG
15 DIM PITCH® Cl)

20 VOICE=0:PITCH=0:TONE=10:V0L=8
38 REM ** C=121:D=108:E=96:F=91
40 TRAP 300
50 PRINT " fS "

66 PRINT "NOTES FOR SIMPLE SONG"

65 FOR NOTE= 1 TO 8
70 READ PITCH

80 SOUND VOICE,PITCH,TONE..VOL

90 GOSUB 20O

100 PRINT: PRINT PITCH®

110 FOR PAUSE=1 TO 500 : NEXT PAUSE
120 SOUND 0,0,0,0
130 NEXT NOTE
140 GOTO 300

150 REM ** DATA FOR NOTES

160 DATA 121,121,108,96,96,91,108,121

2O0 REM ** PRINT NOTES

210 IF PITCH=121 THEN PITCH$="C"

220 IF PITCH=108 THEN PITCH$="D"

230 IF PITCH=96 THEN PITCH$="E"

240 IF PITCH=91 THEN PITCH$="F"

250 RETURN

300 PRINT : PRINT "END OF SIMPLE SONG" : END
RUN

The GOSUB-RETURN and READ-DATA commands allow the computer
to produce different notes by inserting a series of values for the
variable PITCH. GOSUB tells the computer to go to the “subroutine”
that starts at line 200 and continues to line 250; the RETURN com¬
mand sends the computer back to the line immediately below the
GOSUB line. The READ command tells the computer to pick up an
item in the DATA line and insert it into the variable. The computer con¬
tinues to loop through the program until all the values in the DATA line
have been used.

The program also uses a FOR-NEXT loop to determine how long the
notes last. Using different FOR-NEXT loops, try modifying the program
to produce whole notes, half notes, and other kinds of notes.

For more information about programming with sound, refer to the
Resources section of this guide.

COLORFUL GRAPHICS

Your ATARI 130XE has 16 graphics modes encompassing 256 colors.
To get you started, this section presents 6 different modes and some
of the most essential graphics commands.

The following chart lists the 16 basic colors and their corresponding
number values. (The colors vary somewhat according to the adjust¬
ment of the hue control on your television set.)

6 Red-orange

7 Blue

4 Pink

5 Purple

0 Gray
1 Gold

2 Orange

3 Red-orange

8 Blue

9 Light blue

10 Turquoise

11 Green-blue

12 Green

13 Yellow-green

14 Orange-green

15 Light orange

The remaining 112 colors are obtained by adding a value for
luminance, or brightness. The luminance must be an even number
between 0 and 14. The higher the luminance number, the lighter and
brighter the color.

Color registers are another important element in ATARI graphics. The
color registers can be thought of as paint cans. Each register can hold
any of the 128 colors. Because there are five registers, a maximum of
five different colors can be displayed. The five color registers are
numbered 0, 1, 2, 3, and 4.

SETCOLOR is an essential graphics command. The format is
SETCOLOR 2,10,8: the first number is the color register; the second is
the color number; and the third is the luminance.

Graphics Mode 0

The color registers function differently in different graphics modes.
Their functions in graphics mode 0 (the text mode) are shown in the
chart below:

Default Colors Register Function

0 Not used

1 Brightness of text

2 Background

3 Not used

4 Border

Light blue
Dark blue

Black

The default colors are the colors that the computer automatically uses
unless you instruct it to use some other colors. Using SETCOLOR to
change colors, type in the following:

SETCOLOR 2, Z, 4

When you press I Return | , the screen turns orange. The color transfor¬
mation occurs because in the SETCOLOR command, the 2 represents
the screen color, the 3 equals the color orange, and the 4 indicates
the brightness. Change the 4 to a 6. The orange changes to a lighter
orange. Change the 6 to a 7. Nothing happens because only the even

numbers between 0 and 14 define the luminance. If you type an odd
number, the computer uses the color of the previous even number.
Change the 7 to an 8 and watch the color get lighter yet. The following
program shows 128 colors and luminances:

NEM

10 REM »» 128 ATARI COLORS

20 REM ** 16 COLORS

30 FOR C0L0R=0 TO 15

40 REM »» 8 LUMINANCES

50 FOR LUMINANCE=0 TO 14 STEP 2

60 SETCOLOR 2..COLOR..LUMINANCE

65 PRINT "COLOR=";COLOR; M LUMINANCE=";LUMINANCE

70 REM m» PAUSE TO SEE COLOR

80 FOR PAUSE=1 TO 600: NEXT PAUSE

90 NEXT LUMINANCE

100 NEXT COLOR

RUN

When the luminance reaches number 10, the text disappears because
the default luminance of the text is also 10. (The default luminance is
the luminance that the computer automatically uses unless it is
instructed to do otherwise.) Whenever the background luminance is
the same as the text luminance, the text seems to disappear. Pay
attention to background and text luminances as you work more with
color and luminance in graphics mode 0. Type GR.O (which is an
abbreviation for graphics mode 0) to restore the normal screen colors.

Change SETCOLOR 2 to SETCOLOR 4 in line 60 and run the program
again. Because register 4 governs the border, the border changes
color this time instead of the background area. Type GR.O to restore
the normal screen colors.

Graphics Modes 1 and 2

Graphics modes 1 and 2 provide large-size text and color options.
Graphics mode 2 is identical to graphics mode 1 except that each
character is twice as tall. Mode 1 has 24 horizontal screen lines, &nd
mode 2 has 12. To enter graphics mode 1, type

NEM

18 GRAPHICS 1

28 PRINT tt6; "GRAPHICS MODE ONE"

Run the program. Graphics mode 1 is in orange text at the top of the
screen. At the bottom is a blue strip containing the word READY. The
blue strip is the text window and displays text in graphics mode 0.
Type GR.O to return to the text mode.

To print large text on the screen in graphics modes 1 and 2, use
PRINT #6; followed by quotes and then the text that you want to print.
This statement is a variation on the PRINT command that you learned
earlier.

Now list the program. Change MODE to mode and run the program.
MODE turns green. Type LIST 20. Using the Inverse Video keyB,
change mode in line 20 to ■ juiasp and run the program. MODE now
turns blue. List the line again and change EE03 to lMJ.U and run
the program. Now MODE is red.

Enter and run the following program:

NEM

16 REM ** COLORFUL TEXT
20 GRAPHICS 1
30 PRINT »6; "ORANGE"

40 PRINT «6; M green"

50 PRINT «6; "|

60 PRINT »6; "|

70 PRINT "COLORFUL TEXT'
RUN

DARK Rl LJF

As you can see, graphics mode 1 is capable of displaying five colors
at the same time—four different text colors and one background color.
The colors can also be changed by using SETCOLOR according to the
guidelines outlined in the following chart:

Default Color

Character Style

Color#

LUM

Orange

Uppercase

Light green

Lowercase

Dark blue

Inverse uppercase

Red

Inverse lowercase

Black

Background

Type SETCOLOR 4,15,5. Register 4 (the background) changes to a
reddish orange. But now the dark blue text is difficult to read. Use
SETCOLOR to change it. According to the chart, register 2 controls
the dark blue text. SETCOLOR 2,8,6 does the trick by making the dark
blue text a little bit lighter. Add the following lines to the Colorful Text
program:

100 FOR C0L0R=0 TO 15

110 SETCOLOR 2,COLOR,8

120 FOR DELAY=1 TO 400:NEXT DELAY

130 NEXT COLOR

Run the program. The text window at the bottom of the screen
changes color along with the dark blue text because register 2
governs the text window as well as the text display.

Getting Rid of the Text Window

Sometimes you may not want the text window to appear in your pro¬
grams. To eliminate the text window, simply add 16 to the graphics
mode number. Change line 20 to GRAPHICS 17 and delete line 70.

The PRINT command will always print in graphics mode 0. If you are
in modes 1 or 2, if you don’t have a text window, and if you use the
PRINT command and the PRINT #6; command, the computer gets
confused and prints everything in mode 0. Add this line:

70 PRINT "MINDOM TEST"

Run the program to see what happens. If you use PRINT and PRINT
#6; you must use a text window to have mode 1 show up on the
screen.

Delete lines 100, 110, 120, and 130. Run the program. WINDOW TEST
and then READY appear at the top of the screen. List the program.
Line 20 specifies mode 17 (mode 1 without the text window), but
where is it? Replace line 70 with this line:

70 GOTO 70

When you run the program, the mode 1 screen comes back. When
you use mode 1 or 2 without a text window, you must use a GOTO
loop to keep the display on the screen or it will flash by too fast to be
seen. Pressing the I Break I key returns you to mode 0.

To see an example of mode 2, list the Colorful Text program and
change line 20 to

20 GRAPHICS IS

Graphics 18 stands for mode 2 plus 16 (no text window). Run the
program. Now you have LARGE colorful text.

To return the screen to its original colors, press the I Reset I button or
type SETCOLOR 2,9,4. You will not lose your program when you press
I Reset I in ATARI BASIC. However, that feature may not apply to other
languages or programs.

Graphics Mode 3

The graphics mode 3 screen is a grid consisting of 40 columns and 24
rows (20 if you use the text window). Enter and run the following
program:

NEM

10 GRAPHICS 3
28 COLOR 1
30 PLOT 0,0
RUN

In the upper left corner is an orange block. The block, or pixel, is one
unit in the graphics screen. The COLOR command determines the
color of the pixel. The number after the COLOR command determines
which color register to use for the color of the pixel. The COLOR com¬
mand does not place a color in the register; SETCOLOR does that. The
COLOR command simply selects which register to use to plot the
pixel, and the pixel becomes whatever color is in the register. To make
this clearer, change line 20 to

20 COLOR 2

Run the program. The orange pixel is now light green. Think of each
pixel as a text character. In modes 1 and 2, you used uppercase and
lowercase characters and Inverse Video to select the colors of the
text. In modes 3 and above, use the COLOR command to select the
color for the pixels.

PLOT: Plotting Points on the Grid

PLOT is like the PRINT #6; command except that it prints pixels in¬
stead of letters and numbers. COLOR is like the upper/lower/inverse
color selection method; it selects the register. The default colors are
orange, light green, dark blue, and black. To change the color in any
of the registers, use the SETCOLOR command.

The color registers are like four buckets of paint. SETCOLOR selects
the color that goes into each of the four buckets, and COLOR selects
the bucket into which the paintbrush will be dipped. PLOT determines
where the brush will be positioned on the screen.

DRAWTO: Connecting the Dots

Add this line:

40 DRAWTO 39,0

Run the program. A light green line goes across the top of the screen.
After plotting a pixel, use the DRAWTO command to plot a second
pixel and draw a connecting line between the two. Line 40 tells the
computer to plot a pixel at column 39, row 0, and then connect them.
Now type

DRAWTO 39/19

The command plots a pixel in the bottom right corner of the graphics
screen, just above the text window, and then draws a line to connect
39,0 to 39,19. Now type

DRAWTO 0,19

To complete the rectangle, type

DRAWTO 0/0

Now type GR.O and list the program. Add these lines:

50 DRAWTO 39/19
60 DRAWTO 0/19
70 DRAWTO 0/0

SETCOLOR and COLOR

When you run the program, the computer draws a green rectangle
again. To brighten up the screen, type

35 COLOR 1
45 COLOR 2
55 COLOR 1
65 COLOR 3

Run the program to see a rectangle of many colors.

To change the color in a register, use SETCOLOR. You might conclude
that COLOR 1 selects the color for register 1 and that COLOR 2
selects the color for register 2. Unfortunately, that conclusion is not
quite true. Mode 3 has four registers and four colors—but the
registers are numbered 0, 1, 2, and 4, and the colors are numbered 0,

1, 2, and 3. To keep things straight, make a chart:

Color 0 = Register 4
Color 1 = Register 0
Color 2 = Register 1
Color 3 = Register 2

Black
Orange
Light green
Dark blue

Type GR.O, list the program, and change COLOR 2 in line 20 to
COLOR 1. COLOR 1 selects register 0, and orange is the default color
for register 0. To change the color in register 0, use the SETCOLOR
command. Add the following line:

15 SETCOLOR 0..4..6

When you run the program, the orange lines change to a pinkish color.
You have changed the color of the lines by using SETCOLOR to
change the paint in the bucket (the color in the register), not by using
COLOR to choose a different bucket (register). The color luminance of
register 0 also affects the luminance of the text in the text window.

Now add

42 SETCOLOR 1,2,8

The light green at the right side of the box turns gold. Add one more
line:

62 SETCOLOR 2,11,4

Run the program. Not only does the left side of the box change to
green, but the text window also turns green. Therefore, register 2 also
controls the color of the text window.

Now you should be able to use SETCOLOR and COLOR to achieve a
wide variety of colors and hues in your programs.

Graphics Modes 5 and 7

The differences among modes 3, 5, and 7 can be illustrated very
easily. Change line 10 to

10 GRAPHICS 5

Run the program. The rectangle is much smaller because the pixels
are smaller. With the text window, the mode 3 grid has 40 columns
and 20 rows. The mode 5 grid has 80 columns and 40 rows.

Now change line 10 to

10 GRAPHICS 7

When you run the program, an even smaller rectangle appears. The
grid in mode 7 is 160 columns by 80 rows.

The smaller the pixels, the higher the resolution. Of the three modes,
mode 3 is the lowest and mode 7 is the highest. Try drawing a rec¬
tangle around the screen borders in modes 5 and 7.

The following program illustrates all that you have tried in this section.
Type it in and run it:

NEH

5 REM ** BILL 1 5 BOX CPLOT AMD DRAM)

IB PRINT "HHICH MODE C3,5, OR 73"

20 LEFT=0:TOP=0
30 INPUT MODE

40 IF M0DE=3 THEN RIGHT=39:B0TT0M=19
50 IF M0DE=5 THEN RIGHT=79 : B0TT0M=39
60 IF M0DE=7 THEN RIGHT=159 : B0TT0M=79
70 GRAPHICS MODE

80 PRINT 11 GRAPHICS MODE n ;MODE

90 FOR COUNT=l TO 1000

100 COLOR 2

110 TRAP 240

115 REM ** DRAW BOX

120 PLOT LEFT,TOP

130 COLOR 1

140 DRAWTO RIGHT, TOP

150 COLOR 2

160 DRAHTO RIGHT,BOTTOM
170 COLOR 1

180 DRAWTO LEFT,BOTTOM

190 COLOR 3

200 DRAWTO LEFT,TOP

205 REM ** DELAY LOOP

210 FOR DELAY=1 TO 500: NEXT DELAY

215 REM ** SIZE OF NEXT BOX

220 LEFT=LEFT + 2 S T0P=T0P + 2:RIGHT=RIGHT—2:B0TT0M=B0TT0M-2
230 NEXT COUNT

240 PRINT " THAT 1 S ALL FOLKS ! "

250 END

Try using SETCOLOR to change the colors in the Bill’s Box program.

You can learn a great deal more about ATARI graphics, including how
to use other graphics modes and create animated characters. Refer to
Appendix F: Resources to locate books, magazines, and users groups
that can help you further explore the world of ATARI BASIC and your
ATARI 130XE Computer.

Part 3

Appendices

A. Sample Programs

j *V . yy | i

Your ATARI Computer can work miracles with a little help from your
imagination and the right programming techniques. These sample pro¬
grams will show off the versatility of your ATARI 130XE and motivate
you to try writing some programs yourself.

Just type in each program exactly as written, pressing | Return I at the
end of every line. When you’re finished, type the word RUN, press
I Return I , and watch your ATARI Computer come to life.

Note: When spacing in program lines is critical, a note at the bottom
of the program will specify the exact number of spaces needed.

THE ATARI CHOO-CHOO

Sound effects are an ATARI specialty. If you close your eyes when you
run ATARI Choo-Choo, you might think you're on the Marrakesh
Express.

IS POKE 764,255: POKE 580,1

20 GRAPHICS 17: POKE 712,140: POSITION 1,10:PRINT «6;
"THE ATARI CHOO-CHOO"

30 FOR K=15 TO O STEP -l-P:SOUND 1,0,0,H
40«t=INTCRND C0)*300) + l

50 IF R=30 THEN SOUND 3, 36, 10, 10: SOUND 2, 48, 10,

10 : GOSUB 9tf: SOUND 3,0,0,0 : SOUND 2, 0, 0, 0
60 NEKT K : P=P + 0.03
70 IF P>=5 THEN P=5
80 GOTO 30

90 POKE 77,0: POSITION 8,12: PRINT »6; "toot": FOR A=1 TO
400: NEKT A: POSITION 8,12: PRINT 1*6;" ": RETURN

Note: Line 90 requires four blank spaces between the quotation
marks.

THE BIG BANG

Close the door before you run the next program so that you won’t
disturb the neighbors.

10 POKE 764,255:P0KE 580, 1
20 GRAPHICS 17

30 FOR X=10 TO 100: SOUND 0, X, 10, 10 : SOUND 1, X-2, 10, 8:
SOUND 2, X + 2, 10, 12 : NEXT X
40 SOUND 1, 0, 0, 0 : SOUND 2, 0, 0, 0
50 POSITION 4,11: PRINT "BAROOOOMMM!"

60 FOR DECAY=15 TO 0 STEP -0.5: FOR B=1 TO 20:

SOUND 0,100,B,DECAY: POKE 712,B:NEXT B : NEXT DECAY
70 GRAPHICS 1 + 32 : POKE 712, 148

88 POKE 752,1: PRINT : PRINT " Press Start to set off
another explosion."

90 IF PEEK£53279J<>6 THEN GOTO 90
100 GOTO 20

SORT THOSE WORDS

This sorting program puts words in their proper places—in alphabetic
order. Replace the words in the DATA statements in lines 10 and 20 to
sort words of your own choosing. Remember to separate each of your
words with a comma.

10 DATA ATARI,DISK DRIVE, MONITOR,COMPUTER,TOUCH
TABLET,PRINTER,KEYBOARD

20 DATA SOFTWARE,PROGRAM RECORDER,WORD PROCESSING,

ACCOUNTING,DATA BASE,FUN

30 DIM ZSC1000J,AC50J,ASC20J,SC10J

40 S(1J =1:FOR L = 1 TO 9: SCL + 1J=SCLJ*3 + 1:NEXT L

50 TRAP 80 : GRAPHICS 0:? "HERE IS THE LIST : "

60 READ AS:B = LEN(ZS>:C=LENCAS>: ZS
(B+1,B+1)=CHRSCCJ:? AS

70 Z$CB + 2,B + 1 + CJ=AS: Q=Q + 1:ACQJ=B + 1:GOTO 60
80 ? :? "READY TO SORT. . .",:P=0
90P = P + l:IFStP + 2J<Q THEN 90

100 FOR I = P TO 1 STEP -1:S=SCIJ : FOR J=S + 1 TO
Q:L=J-S:A=ACJ) : B=ACLJ

110 IF Z$CA + 1,A + ASCCZ$CA,A>>J>Z$ CB+1,B+ASC£Z$£B,BJ)}
THEN 130

120 A£L+SJ=B:L=L-S:IF L>0 THEN B=AEL) : GOTO 110
130 ACL + S)-A:NEXT J: NEXT I:? : ? "SORTED. "

140 FOR L = 1 TO 0:A = ACL): ? Z$£A+1,A+ASC£ZSEA,AJJ)iNEXT L

PLAYERS AND MISSILES

This program uses a technique called Player Missile Graphics to
create a pink monster that moves across your screen in front of a blue
vertical bar. If you want to make the monster scoot behind the blue
bar, simply change line 150 to 150 poke 623,4.

19 POKE 764,255 : POKE 589,1

29 GRAPHICS 3 + 16

30 FOR H=16 TO 24 : FOR Y=0 TO 23 : COLOR 3 : PLOT H, Y : NEHT
Y:NEXTH

40 MEMTOP—PEEK C 7413 +256*PEEK C 7423—1

59 PMBASE=INT££MEMTOP-10243 /19243 *1024

60 ADJT0P=PMBASE + 384

70 POKE 742,INT £ADJT0P/2563 :

POKE 741,ADJTOP—256*PEEK C 742 3
80 POKE 54275,PMBASE/256
50 POKE 53277,2
100 POKE 555,34 + 8
110 P0=PMBA5E + 512

129 FOR A=PO TO PO + 128 : POKE A,0: NEHT A

130 FOR A=PO + 60 TO P0 + 67:READ B: POKE A , B : NEHT A
140 POKE 53256,3

150 POKE 623,1
160 POKE 704,108

170 POKE 53248,PEEKC203 : GOTO 170
180 DATA 60,126,125,153,255,36,66,125

TOPSY-TURVY

When you run Topsy-Turvy, your screen will be filled with strange
writing. To straighten it out, simply press rstarTI . To mess things up
again, press fseiect I

10 POKE 764,255: POKE 580,1

20 GRAPHICS 18: POKE 712,128: POKE 755,5
30 POSITION 5,3: PRINT «6; WELCOME TO"

40 POSITION 2,5:PRINT «6; "THE TOPSY-TURUY ,J :POSITION
6^7:PRINT tt6; "WORLD OF": POSITION 6,5
50 PRINT tt6;" COMPUTERS"

60 IF PEEK£53275 3=5 THEN POKE 755,5:POKE 712,128
70 IF PEEK £532753 =6 THEN POKE 755,1: POKE 712,55
80 GOTO 60

TYPE-A-TUNE

This program assigns musical note values to the keys on the top row
of the keyboard. Press only one key at a time.

MUSICAL VALUE

l B

B (or A#)

L A

A p (or G#)

G t

F#(or G p )

i E

E p (or D#)

L D

D b (or C#)

10 DXM CH0RDC37),TUNEC123

20 GRAPHICS 8 : ? 5 ? " TYPE—A—TUNE PROGRAM"

25 ? : ? "PRESS KEYS 1-9,0,<,> TO PRODUCE NOTES.

27 ?: ? "RELEASE ONE KEY BEFORE PRESSING THE NEKT . "

28 ?:? "OTHERWISE.. THERE MAY BE A DELAY. "

30 FOR K=1 TO 37: READ A : CHORDCK)=A:NEKT K
40 FOR H=1 TO 12: READ A:TUNECK)=A:NEKT K
50 OPEN til,4,0, "K: "

55 OLDCHR=—1

60 A=PEEKC7643 : IF A=255 THEN 60
63 IF A=OLDCHR THEN 100
65 OLDCHR=A

70 FOR K=1 TO 12: IF TUNECK3=A THEN SOUND
0,CHORDC K 3,10,8:GOTO 100
80 NEKT K

100 I=INTCPEEKC537753/43:IF CI/23=INTC1/23 THEN 60

110 POKE 764,255: SOUND 0,0,0,0 : OLDCHR=-l :GOTO 60

200 DATA 243,230,2J.7,204,193,182,173,162,153,144,136,

128,121,114,108,102,96,91,85,81,76,72,68,64,60

210 DATA 57,53,50,47,45,42,40,37,35,33,31,29

220 DATA 31,30,26,24,29,27,51,53,48,50,54,55

To play "Mary Had a Little Lamb,” press the following keys:

5,3,1, 3, 5, 5, 5 3, 3, 3 5, 8,8 5, 3, 1, 3, 5, 5, 5 5, 3, 3, 5, 3, 1

Note: Make sure you insert three spaces between THE and NEXT in
line 27.

KEY

Insert

Clear

HIGHER MATH

Your ATARI Computer is a fancy calculator. When you enter two
numbers into the program below, the computer will tell you their
greatest common denominator. For example, if you enter 690911 and
11214017, you’ll soon discover that their greatest common
denominator is 53147.

10 ? CHR$C125 3 :? "Enter two nuhbers. Press Return after
each entry. 11
20 INPUT N1N2
30 GOSUB 30

40 ? "Their GCD is AN

50 POKE 752^1: POSITION 10.. 10: ? "Press Start to
continue."

60 IF PEEK(53273306 THEN GOTO 60
70 POKE 752^0:? CHR5C125) : GOTO 10
80 REM ****SUBROUTINE****

30 AN=0 : POKE 135 ..0 : TRAP 130: M= C N1> = N2 J*N1 + C N2>N1 J*N2
N=CM=N13*N2+CM=N2}*N1

100 IF INTCN1JON1 OR INT CN23 0N2 THEN RETURN
110 P=M—INT CM/N3*N:M=N:N = P
120 IF POO THEN GOTO 110
130 ftN=M*CPEEKCl35J=03 :RETURN

COMPUTER BLUES

This program generates random musical notes to “write'’ some very
interesting melodies for the programmed bass,

1 GRAPHICS e : ? : ? " COMPUTER BLUES" : ?

2 PTR=1

3 THNOT—1

5 CHORD=l

6 PRINT "BASS TEMPO tl=FAST3 " - !

7 INPUT TEMPO

8 GRAPHICS 2 + 16 : GOSUB 2099
IB DIM BASEC 3^ 43

20 DIM LOMC 3 3

25 DIM LINEC16 3

26 DIM JAMC3 ^73

39 FOR H=1 TO 3

40 FOR Y=1 TO 4

50 READ A : BASECK^Y3=A
60 NEKT Y
70 NEKT K

80 FOR K=1 TO 3: READ A:LOMCK3=A
SO NEKT K

95 FOR K=1 TO 16:READ A:LINE(K3=A SNEKT K

96 FOR K=1 TO 3

97 FOR Y=1 TO 7

98 READ A : JAM(K^Y3=A : NEKT Y : NEKT K
100 GOSUB 500

110 T=T + 1
115 GOSUB 200
120 GOTO 100

20O REM PROCESS HIGH STUFF

205 IF RNDC0J<0.25 THEN RETURN

210 IF RNDCO3 <0.5 THEN 250

220 NT=NT + 1

230 IF NT>7 THEN NT=7

240 GOTO 260

250 NT=NT-1

255 IF NT<1 THEN NT=1

260 SOUND 2^ JAMC CHORD^NT 3 ^10 ^ NT*2

280 RETURN

500 REM PROCESS BASE STUFF
510 IF BASS=1 THEN 700
520 BDUR=BDUR + 1

530 IF BDUR< >TEMPO THEN 535

531 BASS=1:BDUR=0

535 SOUND 0 s LOW t CHORD 3^10^4

540 SOUND l / BASEtCHORD / THNOT3^10 (F 4

550 RETURN

700 SOUND 0,0,0,0

710 SOUND 1,O,O,0

720 BDUR=BDUR + 1

730 IF BDUROl THEN 800

740 BDUR=0 : BASS=0

750 THN0T = THN0T + 1

760 IF THN0TO5 THEN 800

765 THN0T = 1

770 PTR=PTR+1

780 IF PTR=17 THEN PTR=1

790 CHORD—LINEtPTR)

800 RETURN

1000 DAT A 162,144,136,144,121,108,102,108,108,96,91,96
1O10 DATA 243,182,162

1020 DATA 1,1,1,1,2,2,2,2,1,1,1,1,3,2,1,1

1O30 DATA 60,50,47,42,40,33,29

1040 DATA 60,50,45,42,40,33,29

1050 DATA 81,68,64,57,53,45,40

2000 PRINT «6: PRINT »6: PRINT »6

2005 PRINT «6;" Cowputer"

2006 PRINT »6

2O10 PRINT »6; 11 Blues"

2030 RETURN

UNITED STATES FLAG

This program involves switching colors to set up the stripes. It uses
graphics mode 7 plus 16 so that the display appears as a full screen.
Note the correspondence of the COLOR statements with the
SETCOLOR statements. For fun and experimentation purposes, add a
SOUND statement and use a READ/DATA combination to add “The
Star Spangled Banner” after line 470.

10 REM DRAM THE UNITED STATES FLAG

20 REM HIGH RESOLUTION 4-COLOR GRAPHICS.. NO TEHT WINDOW
30 GRAPHICS 7 + 16

40 REM SETCOLOR 0 CORRESPONDS TO COLOR 1
50 SETCOLOR 0..4..4:RED = 1

60 REM SETCOLOR 1 CORRESPONDS TO COLOR 2

70 SETCOLOR 1.. 0.. 14 : WHITE = 2

80 REM SETCOLOR 2 CORRESPONDS TO COLOR 3

30 BLUE = 3 : REM DEFAULTS TO BLUE

100 REM DRAW 13 RED & WHITE STRIPES

110 C = RED

120 FOR 1 = 0 TO 12

130 COLOR C

140 REM EACH STRIPE HAS SEVERAL HORIZONTAL LINES

150 FOR J = 0 TO 6

160 PLOT 0..I*7 + J

170 DRAWTO 153 1*7 +J

180 NEXT J

130 REM SWITCH COLORS

200 C = C + 1:IF C>WHITE THEN C=RED

210 NEXT I

300 REM DRAW BLUE RECTANGLE

310 COLOR BLUE

320 FOR I = 0 TO 48

330 PLOT 0^1

340 DRAWTO 73..I

350 NEXT I

360 REM DRAW 3 ROWS OF WHITE STARS
370 COLOR WHITE

380 K = 0 : REM START WITH ROW OF 6 STARS
330 FOR 1=0 TO 8
335 Y = 4 + I*5

40O FOR J = 0 TO 4 : REM 5 STARS IN A ROW
410 X = K + 5 + J*14:GOSUB 1000
420 NEXT J

430 IF K<>0 THEN K = 0:GOTO 470

440 REM ADD 6TH STAR EVERY OTHER LINE
450 H=5+5*14 : GOSUB 1000
460 K=7
470 NEKT I

500 REM IF KEY HIT THEN STOP
510 IF PEEK£764)=255 THEN 510

515 REM OPEN TEHT WINDOW WITHOUT CLEARING SCREEN

520 GRAPHICS 7 + 32

525 REM CHANGE COLORS BACK

530 SETCOLOR 0,4^4: SETCOLOR 1,0,14

550 STOP

1000 REM DRAW 1 STAR CENTERED AT H,Y
1010 PLOT H—1, Y : DRAWTO H + 1,Y
1020 PLOT H, Y-l: PLOT H,Y+1
1030 RETURN

IGPAY ATINLAY

This short program converts words or sentences into pig Latin. One
word of caution, though; don’t enter any one-letter words like A or I.

16 DIM ASC2563 :S = 2

26 ? "Type in a word or sentence. Please don 1 1 exceed
three lines of text. "

36 INPUT AS

40 FOR X=1 TO LENC AS J

50 IF ASCX^K)=:CHRSC32) THEN PRINT

ASCS^X-lJ^ASCS-l^S-lJ; "AY".:" "; :5=X+2

60 IF X=LENC AS3 THEN PRINT ASC5^X).i A$CS-1^5-1J; "AY"

70 NEXT X

80 ? : ? : ? "THAT'S ALL FOLKS! "

GRAPHEEK

Just type this one in and watch the graphics action.

10 DIM ASC35)

20 GRAPHICS 1
25 TRAP 90

30 A$ = "THIS IS A GRAPHICS DEMONSTRATION."

40 FOR 1=1 TO 33i? tt6;A$CI,I);

50 S=PEEKC537701
60 SOUND O/S/10/14
70 FOR DELAY=0 TO 100: NEXT DELAY
80 NEXT I

90 SOUND 0/0,0/0:END

Note: Make sure you insert two spaces between GRAPHICS and
DEMONSTRATION in line 30.

ESREVER

The title of this program is simply the word REVERSE printed in reverse.
To print words spelled backward, just type in this short program. After
you run it, a question mark will appear on your screen. Enter a word
or a short sentence and let your ATARI 130XE do all the work.

10 DIM ASC1803

20 PRINT "Enter a word or short sentence and press
Return,"

30 INPUT AS

40 FOR X=LENCAS3 TO 1 STEP -I
50 PRINT ASCX^X? ^

60 NEXT X

70 PRINT : PRINT : GOTO 20

PROTECTING YOUR PROGRAM

Ever wonder how you could protect your programs from prying eyes
and quick fingers? A couple of programming tips can help keep
pilferers out of your programs.

First type in this program:

10 FOR H=1 TO 50:POKE 710,X; NEXT X:GOTO 10

To protect the program, add another program line to disable the
1 Break I key. This line prevents someone from breaking into the
program and listing it while it's running. Also, if you design a program
that requires keyboard entry, disabling the I Break I key protects against
“finger slip,” that dreaded mishap when your finger accidentally hits
the i Break I key and brings your program to a screeching halt.

Delete GOTO 10 from the colorful program and add this line:

20 POKE 16/64:P0KE 53774,64: GOTO 10

Now run your new program and try to stop it by pressing the 1 Break |
key. You can’t get into it.

To be effective, the POKE statements must be inserted in your
program after each graphics mode command.

Disabling the | Break 1 key has its limitations. Some smart programmer
will figure out that he or she can break into your program and list it by
simply pressing the [ Reset I key. To foil this culprit, add this line to your
program:

5 POKE 580,1

Now when the inquisitive intruder presses I Reset I , the flashing colors
program is purged from the computer’s memory—no program, no
listing! The POKE statement should always be at the beginning of your
program.

SEA GULL OVER OCEAN

This program combines graphics and sounds. The sounds are not
"pure” sounds; they simulate the roar of the ocean and the gull’s cry.
To get the symbols in line 20, use I Control I [G] , | Control | fFl . [Control |
El, I Control I [R] .

10 DIM BIRDSC4)

20 BIRDS="\/—"

30 FLAG=1:ROH=10:COL=10

40 GRAPHICS 1: POKE 756,226 : POKE 752,1

50 SETCOLOR 0,0,0 : SETCOLOR 1,8,14

60 print *16; " the ocean"

70 R=INTCRNDC0)*11>

80 POSITION 17,17
90 FOR T=0 TO 10
100 SOUND 0,T,8,4
110 FOR A=1 TO 50 : NEXT A

120 IF RNDC0) >0.8 THEN FOR D=10 TO 5 STEP -1: SOUND
1,0,10,INTCRNDC0)*10):NEXT D: SOUND 1,0,0,0
130 GOSUB 200
140 NEXT T

150 FOR T=10 TO 0 STEP -1

160 SOUND 0,T,8,4

170 FOR A=1 TO 50: NEXT A

175 IF RNDC0) >0.8 THEN FOR D=10 TO 5 STEP

-ItSOUND 1,D,10,8: NEXT D : SOUND 1,0,0,0

180 FOR H=1 TO 10 : NEXT H

185 GOSUB 200

190 NEXT T

195 GOTO 70

200 GOSUB 300

210 POSITION COL,RON

220 PRINT tt6^BIRDSCFLAG,FLAG+1)

230 FLAG=FLAG + 2 : IF FLAG=5 THEN FLAG=1
240 RETURN

300 IF RND C0 ) >0.5 THEN RETURN

310 POSITION COL,ROM

320 PRINT »6; 11 11

330 A=INTCRNDC0)*3)-1

340 B=INTCRNDC0)*3>—1

350 ROH=ROH+A

360 IF ROH=0 THEN ROM=l

370 IF ROH=20 THEN R0M=19

380 COL=COL + B

390 IF COL=0 THEN COL=l

400 IF C0L>18 THEN C0L=18

410 RETURN

Note: Two spaces are required between the quotation marks in
line 320. 90

KINETIC ART

Put colors in motion with a program that creates a rainbow of
continually moving lines.

18 REM KINETIC ART BY NEIL HARRIS
28 GRAPHICS 10
30 DIM AI3/50)

35 FOR L=0 TO 3 : FOR M=0 TO 50 : ACL/M)=0 : NEXT M: NEXT L
40 HUE=INTIRNDt1)*8+1):POKE

704+HUE/INTtRNDtl)*8)*16+INTtRNDtl)*4+4)

50 Xl=INTtRNDtl)*80):X2=INTtRNDtl)*80)

:Y1=INTCRNDC1)*192):Y2=INTCRNDC1)*192)

60 COLOR 0:PLOT At0,WHICH) ,Atl,WHICH) : DRAHTO
At 2.. WHICH).. At 3.. WHICH!

70 BOIINCE=BOUNCE—1: IF BOUNCE>0 THEN 90
80 BOUNCE=INT£RND£1)*10+10):BX1=INTfRND11)*9-4)
:BX2=INT£RNDtl)*9—4):BYI=INT£RND£1)*13—6)

:BY2=INTCRNDCl)*13-6)

90 CHANGE=CHANGE—1: IF CHANGE>0 THEN 110

100 CHANGE=INTCRND£l)*10+5):HUE=INTtRND11)*8 + l):POKE
704+HUE,INTtRNDtl)*256)

110 COLOR HUE! PLOT XI.. Y1: DRAWTO X2/Y2

120 At0/WHICH)=X1:At1/WHICH)=Y1:At2 ..WHICH) =X2:A

t3/WHICH)=Y2

130 WHICH=WHICH + 1: IF WHICH>50 THEN WHICH=0
140 X1=X1 + BX1: IF X1<0 OR Xl>79 THEN BX1 = -BX1: GOTO 140
150 X2=X2 + BX2 : IF X2<0 OR X2>79 THEN BX2=-BX2 : GOTO 150
160 Y1=Y1 + BY1: IF Y1<0 OR Yl>191 THEN BY1=-BY1: GOTO 160
170 Y2=Y2 + BY2 : IF Y2<0 OR Y2>191 THEN BY2=-BY2 : GOTO 170
180 GOTO 60

B. BASIC Reserved Words

Note: The period is mandatory after all abbreviated keywords.

RESERVED BRIEF SUMMARY

WORD ABBREVIATION OF BASIC STATEMENTS

ABS Returns the absolute (unsigned) value

of the variable or expression.

ADR Returns the memory address of a

string variable.

AND Functions as a logical operator. The

expression is true only if both
subexpressions joined by AND are
true.

ASC Returns the numeric value of a single

string character.

ATN Returns the arctangent of a number

or expression in radians or degrees.

BYE B. Exits from BASIC and returns to the

resident operating system or console
processor.

CLOAD CLOA. Loads data from the program

recorder into RAM.

CHR$ Returns a single string byte

equivalent to a numeric value
between 0 and 255 in ATASCII code.

CLOG Returns the base 10 logarithm of an

expression.

CLOSE CL. Closes a file at the conclusion of I/O

operations. Functions as an I/O
command.

CLR Performs the opposite function of

DIM: undimensions all strings and
matrices.

COLOR

C. Chooses the color register to be used

in color graphics work.

COM

Performs the same function as DIM.

CONT CON.

COS

CSAVE

DATA D.

DEG DE.

DIM Dl.

DOS DO.

DRAWTO DR.

END

ENTER E.

Stands for “continue." Causes a
program to restart execution on the
next line after being stopped by the
I Break I key or encountering STOP.

Returns the cosine of the variable or
expression in degrees or radians.

Outputs data from RAM to the
program recorder for tape storage.

As part of the READ-DATA
combination, identifies the
succeeding items (which must be
separated by commas) as individual
data items.

Tells the computer to perform trigono¬
metric functions in degrees instead of
radians. (The default measurement is
in radians.)

Reserves the specified amount of
memory for matrix, array, and string
variables. (All string variables, arrays,
and matrices must be dimensioned
with a DIM statement.)

Stands for “Disk Operating System.”
Causes the menu to be displayed.

(See DOS manual.)

Draws a straight line between a
plotted point and a specified point.

Stops program execution; closes files;
turns off sounds. May be used more
than once in a program. (CONT can
be used to restart the program.)

Stores data or program in
untokenized (source) form. Functions
as an I/O command.

EXP

Returns e (2.7182818) raised to a
specified power.

FOR

Used with NEXT to establish FOR-
NEXT loops. Introduces the range
that the loop variable will operate in
during the execution of the loop.

FRE

Returns the amount of remaining user
memory in bytes.

GET

GE.

Used mostly with disk operations to
input a single byte of data.

GOSUB

GOS.

Branches to a subroutine beginning at
a specified line number.

GOTO

Branches unconditionally to a
specified line number.

GRAPHICS

GR.

Specifies one of the 16 graphics
modes. (GR.O can be used to clear
the screen.)

Causes conditional branching or the
execution of another statement on
the same line (only if the first
expression is true).

INPUT

1 .

Causes the computer to ask for input
from the keyboard. Execution con-
tinues only when the iRetuml kev is
pressed after data have been inputted.
Also functions as an I/O command.

INT

Returns the next lowest whole integer
below a specified value. (Rounding is
always downward, even when the
number is negative.)

LEN

Returns the length of the specified
string in bytes or characters. (One
byte contains one character.)

LET

LE.

Assigns a value to a specific variable
name. (LET is optional in ATARI

BASIC and can be omitted.)

LIST

LOAD LO.

LOCATE LOC.

LOG

Displays or otherwise outputs the
program list.

Inputs from a disk into the computer.

Stores in a specified variable the
value that controls a specified
graphics point.

Returns the natural logarithm of a
number.

LPRINT LP.

NEW

Commands the line printer to print a
specified message.

Erases all contents of user RAM.

NEXT N.

NOT

NOTE NO.

OPEN 0.

PADDLE

Causes a FOR-NEXT loop to
terminate or continue, depending on
the particular variables or expres¬
sions. (All loops are executed at least
once.)

Returns a 1 only if the expression is
not true; returns a 0 if it is true.

Used only in disk operations.

(See Disk Operating System manual.)

Used with GOTO or GOSUB for
branching purposes. (Multiple
branches to different line numbers
are possible, depending on the value
of the ON variable or expression.)

Opens the specified file for input or
output operations.

Used as a logical operator between
two expressions. If either one is true,
a 1 is evaluated; if both are false, a 0
results.

Returns the position of the paddle
game controller.

PEEK

PLOT PL.

POINT P.

POKE POK.

POP

POSITION POS.

Returns the decimal form of the
contents of a specified memory
location (RAM or ROM).

Plots a single point at a specified X,Y
location.

Used with disk operations only. See
Disk Operating System manual.

Inserts the specified byte into the
specified memory location. May be used
only with RAM.

Removes the loop variable from the
GOSUB stack. Used when departure
from the loop is made in an other-
than-normal manner.

Sets the cursor at a specified screen
position.

PRINT PR. or?

PTRIG

PUT PU

RAD

READ REA.

REM R.

Causes output from the computer to
the specified output device. Functions
as an I/O command.

Returns the status of the trigger
button on a game controller.

Causes output of a single byte of data
from the computer to the specified
device.

Tells the computer to give information
in radians, rather than in degrees, for
trigonometric functions. (The default
measurement is radians. See DEG.)

Reads the items in the DATA list and
assigns them to specified variables.

Stands for “remarks.” Does nothing
but allows comments to be printed in
the program list for the programmer’s
future reference. REM statements are
not executed.

RESTORE

RES.

Allows data to be read more than
once.

RETURN

RET.

Returns the computer from a sub¬
routine to the statement immediately
following the one in which GOSUB
appears.

RND

Returns a random number between 0
and 1, but never 1.

RUN

RU.

Executes the program; sets normal
variables to 0; undims arrays and
strings.

SAVE

Causes data and programs to be
recorded on disk under the filespec
provided with SAVE. Functions as an
I/O command.

SETCOLOR

SE.

Stores hue and luminance color data
in a particular color register.

SGN

Returns +1 if the value is positive; 0,
if zero; -1, if negative.

SIN

Returns the trigonometric sine of a
given value in degrees or radians.

SOUND

SO.

Controls register, pitch, distortion,
and volume of a tone or note.

SQR

Returns the square root of a specified
value.

STATUS

ST.

Calls status routine for a specified
device.

STEP

Used with FOR-NEXT. Determines the
quantity to be skipped between suc¬
cessive loop variable values.

STICK

Returns the position of the stick game
controller.

STRIG

Returns 1 if stick trigger button is not

pressed; 0, if pressed.

STOP STO.

STR$

THEN

TRAP T.

USR

VAL

XIO X.

Causes the program to stop but does
not close files or turn off sounds.

Returns a character string equal to
the numeric value given. (For
example, STR$(65) returns 65 as a
string.)

Used with IF. If the expression is
true, the THEN statements are
executed. If the expression is false,
control passes to the next line.

Used with FOR, as in “FOR X = 1
TO 10.” Separates the loop range
expressions.

Takes control of the program in case
of an INPUT error and directs
execution to a specified line number.

Returns the results of a machine-
language subroutine.

Returns the equivalent numeric value
of a string.

Used with disk operations (see Disk
Operating System manual) and in
graphics work. Functions as a
general I/O statement.

100

C.ATASCII Character Set

Decimal

Hexadecimal

ATASCII

European

Code

Character

Keystrokes

Character

Control

Control A

□

Control B

Control C

Control D

Control E

Control F

Control G

Control FI

□

Control 1

Control J

□

Control K

Control L

□

Control M

Control N

Control 0

Control P

Control Q

Notes:

1. ATASCII stands for ATARI ASCII. Letters and numbers have the same
values as those in ASCII, but some of the special characters are different.

2. Except as shown, the characters from 128 to 255 are the reverse colors of
1 to 127.

3. Add 32 to the uppercase code to get the lowercase code for the same letter.

4. To get the ATASCII code, tell the computer (direct mode) to PRINT ASC

(“_”). Fill the blank with a letter or a character. You must use the

quotes!

5. The normal display keycaps are shown as white symbols on a black back¬
ground; the inverse keycap symbols are shown as black symbols on a white
background.

101

Decimal

Hexadecimal

ATASCII

Code

Character

Keystrokes

Control R

ffl

Control S

Control T

Control U

Control V

Control W

Control X

Control Y

Control Z

Esc Esc

Esc Control

Esc Control -

Esc Control +

Esc Control *

□

Space bar

Shift 1

□

Shift 2

Shift 3

Shift 4

Shift 5

Shift 6

□

Shift 7

Shift 9

Shift 0

□

European

Character

102

cin

:od

Hexadecimal

Code

39
3A
3B
3C
3D
3E
3F

49
4A
4B

ATASCII

Character

L5j

Keystrokes

8
9

Shift .

Shift /

Shift 8
A
B
C
D
E
F
G
H
\

European

Character

103

Decimal

Hexadecimal

AT ASCII

Code

Character

Keystrokes

[

Shift ,

Shift +

Shift

Shift *

□

Shift

Control

100

101

102

103

]

104

K..

1 1

105

European

Character

<»

•»

104

icim

;ode

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

Hexadecimal

ATASCII

Code

Character

Keystrokes

6 E

7 A

Control

Shift

Esc Control <

Esc Shift <

Esc Delete Bk Sp

►

Esc Tab

□

W\ Control .

W\ Control A

W\ Control B

W\ Control C

W\ Control D

W\ Control E

□

W\ Control F

European

Character

105

Decimal

Code

Hexadecimal

Code

ATASCII
Character

Keystrokes

135

□

E Control G

136

E Control H

137

E Control 1

138

E Control J

139

E Control K

140

E Control L

141

E Control M

142

E Control N

143

E Control O

144

□

E Control P

145

E Control Q

146

E Control R

147

□

E Control S

148

□

E Control T

149

E Control U

150

■

E Control V

151

□

E Control W

152

□

E Control X

153

E Control Y

154

E Control Z

155

EOL

E Return

156

□

E Esc Shift
Delete Bk Sp

157

□

E Esc Shift >

158

□

E Esc Control
Tab

159

□

E Esc Shift

Tab

160

■

E Space bar

161

E Shift 1

162

E Shift 2

163

E Shift 3

European

Character

106

cimal

:ode

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

Hexadecimal

Code

ATASCII

Character

Keystrokes

B Shift 4

B Shift 5

B Shift 6

■

B Shift 7

B Shift 9

B Shift 0

□

B *

□

B +

B «

B “

B •

B /

B 0

B 1

B 2

B 3

□

B 4

B 5

B 6

B 7

B 8

B 9

B Shift:

B ;

B <

B =

B >

B Shift/

B Shift 8

B A

European

Character

107

Decimal

Code

Hexadecimal

Code

ATASCII
Character

Keystrokes

European

Character

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

□

211

212

213

214

□

215

□

216

□

217

218

219

Shift

220

Shift +

221

Shift

222

Shift *

223

Shift ■

ecim

Zodt

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

Hexadecimal

Code

ATASCII

Character

Keystrokes

□

B Control

B a

B b

B c

B d

B a

□

B f

□

B 9

B h

B i

B j

B k

□

B m

B n

B o

□

B P

□

b d

□

B r

B s

B t

B u

B v

B w

B x

B y

B z

□

B Control

B Shift =

□

Esc Control 2

European

Character

109

Decimal

Code

254

255

Hexadecimal

Code

ATASCII

Character

Keystrokes

European

Character

□

B Esc Control
Delete Bk Sp

W\ Esc Control >

<»

4 »

<»

110

D. Error Messages

ERROR

CODE

NUMBER ERROR CODE MESSAGE

2 Insufficient Memory: Not enough RAM memory is
left to store the statement or the new variable
name, or to dimension a new string array variable.

3 Value Error: A value expected to be a positive
integer is negative; a value is not within a specific
range.

4 Too Many Variables: The maximum of 128 different
variable names has been exceeded.

5 String Length Error: The user attempted to store
string variables that exceeded the dimensioned
string length.

6 Out of Data: The READ statement requires more
data items than the DATA statement(s) supplied.

7 Line Number Greater Than 32767: The line
number reference is greater than 32767.

8 Input Statement Error: The user attempted to input
a nonnumeric value into a numeric variable.

9 Array or String DIM Error: The DIM size exceeded
5460 for numeric arrays or 32767 for strings; an
array or string was redimensioned; reference was
made to an undimensioned array or string.

11 Floating Point Overflow/Underflow: The user
attempted to divide by zero or to refer to a number
larger than 1 x 10 98 or smaller than 1 x 10-".

12 Line Not Found: A GOSUB, GOTO, or THEN
referenced a nonexistent line number.

13 No Matching FOR Statement: A NEXT was

encountered without a previous FOR, or nested
FOR/NEXT statements do not match properly.
(The Error message is reported at the NEXT
statement, not at FOR.)
ill

14 Line Length Error: The statement is too complex or
too long for BASIC to handle.

15 GOSUB or FOR Line Deleted: A RETURN or NEXT
statement was encountered, but the corresponding
GOSUB or FOR has been deleted since the last
RUN command.

16 RETURN Error: A RETURN was encountered
without a matching GOSUB.

17 Syntax Error: The computer encountered a line with
improper syntax.

18 Invalid String Character: The string in the VAL

statement is not a numeric string.

Note: The following errors are INPUT/OUTPUT (I/O) errors that result

during the use of disk drives, printers, or other accessory devices.

Further information is provided with the auxiliary hardware.

19 LOAD Program Too Long: Insufficient memory
remains to complete LOAD.

20 Device Number Error: The device number is larger
than 7 or equal to 0.

21 LOAD File Error: The user attempted to load a non¬
load file, not a BASIC tokenized file. Tokenized files
are created with the SAVE command.

128 Break Abort: The user hit the I Break I key during an
I/O operation.

129 IOCB 1 Already Open: The Input/Output Control
Block is already open.

130 Nonexistent Device: The user tried to access an
undefined device (i.e., a device not in the handler
table).

131 IOCB 1 Write-Only Error: A READ command has
been sent to a write-only device (printer).

132 Invalid Command: The command is invalid for this
device.

133 Device or File Not Open: No OPEN command has
been specified for the device.

134 Bad IOCB 1 Number: The device number is illegal.

135 IOCB 1 Read-Only Error: A WRITE command has
been sent to a read-only device.

136 EOF: The computer has reached the end of the file.

137 Truncated Record: This error typically occurs when
the record being read is larger than the maximum
record size specified in the call to CIO. (BASIC’s
maximum record size is 119 bytes.)

138 Device Time-out: The device doesn’t respond.

139 Device NAK: Problems are located at the serial
port or in the peripheral.

140 Serial Bus Input Framing Error: Information was
lost from the peripheral to the computer.

141 Cursor Out of Range: The cursor is out of range
for a particular mode.

142 Serial Bus Data Frame Overrun: Information was
lost from the peripheral to the computer.

143 Serial Bus Data Frame Checksum Error:

Information was lost from the peripheral to the
computer.

144 Device Done Error: The user attempted to write on
a write-protected diskette.

145 Read After Write Compare Error: The user tried to
open the Screen Editor with an illegal graphics
mode number.

146 Function Not Implemented: The function was not
implemented in the handler.

147 Insufficient RAM: Not enough RAM memory is left
for operating the selected graphics mode.

160 Drive Number Error: The user specified the wrong

drive number.

113

Q. I just tried the computer’s built-in ATARI BASIC. I typed in a
program, but it won’t run. Why not?

A. Make sure you pressed I Return I after each program statement
before typing RUN. When you press | Return | , you are telling the
computer that you are entering information.

Another common mistake is to confuse zeros and capital letter O’
Though they look similar, the computer treats them differently.

F. Resources

ATARI Computer users don’t have to work or play in isolation. Most of
the problems that you might encounter have already been worked out
by others. Much of this experience is documented, so plenty of support
is available. The resources listed here are a few of the many aids that
can guide you into new, rewarding directions in personal computing.
You can obtain the resources by visiting bookstores and ATARI
Computer retailers or by writing to the addresses provided below.

USERS GROUPS

You can share information with other ATARI Computer owners by
joining an ATARI users group. Users groups usually have monthly
meetings and publish a newsletter. Whether you need help in
programming one of several computer languages, advice about
purchasing software, or news about the latest products for your ATARI
130XE, you can find it and more from your local users group. To get
the address of the group nearest you or to find out how to start your
own group, write ATARI Customer Relations, P.O. Box 61657,
Sunnyvale, CA 94088.

BOOKS

ATARI BASIC Reference Manual. Part # C015307. Available from
ATARI Customer Relations, P.O. Box 61657, Sunnyvale, CA 94088.
Cost: $10.95 plus $2.50 for shipping. California residents add 6.5 per¬
cent tax. This manual is the most complete reference on ATARI
BASIC. It features a complete description of every command and func¬
tion and gives examples.

Technical Reference Notes. Part # C01655. Available from ATARI
Customer Relations, P.O. Box 61657, Sunnyvale, CA 94088. Cost:
$29.95 plus $2.50 for shipping. California residents add 6.5 percent
tax. This manual is a technical reference volume for the advanced pro¬
grammer and the software developer.

Inside ATARI BASIC: A Fast, Fun, and Friendly Approach by Bill Carris.
Reston Publishing Co., 11480 Sunset Hill Road, Reston, VA 22090. This
excellent book for beginners picks up where the ATARI 130XE Owner’s
Manual leaves off.

Your ATARI Computer by Lon Poole, Martin McNift, and Steven Cooke.
Osborne/McGraw-Hill, 630 Bancroft Way, Berkeley, CA 94710. This
general reference has a major emphasis on intermediate-to
advanced-level programming in ATARI BASIC.

Dr. Wacko’s Miracle Guide to Designing and Programming Your Own
Arcade Games by David Heller, Addison-Wesley, Reading, MA 01867.
This step-by-step tutorial for writing arcade-style games in ATARI
BASIC is entertaining and educational.

MAGAZINE

ATARI EXPLORER. Every issue of the ATARI EXPLORER is designed to
help you get more out of your ATARI Computer. Subscribe immediately
and save 50 cents off the cover price—6 issues for $15.00. Or save
25 percent by subscribing for 18 issues for $39.95. Send a check or a
money order to ATARI EXPLORER, P.O. Box 3427, Dept. X, Sunnyvale,
CA 94088-3427.

CUSTOMER RELATIONS

For questions or problems regarding ATARI products, write to ATARI
Customer Relations, P.O. Box 61657, Sunnyvale, CA 94088 or call
(408)745-4851.

G. ATARI 130XE Specifications

Processor:

6502C Microprocessor, clock speed 1.79 MHz

Custom Chips:

GTIA chip—graphics display

POKEY chip—sound generator and control

ANTIC chip—screen and input/output ports
FREDDY chip—memory system control

Memory:

131,072 bytes of RAM

24,576 bytes of ROM (operating system plus ATARI
BASIC programming language)

Display:

11 graphics modes

256 colors

320 x 192, highest graphics resolution

40 columns x 24 lines text display

5 text modes

Sound:

4 independent sound voices

3 1 12 octave range

Keyboard:

Full-stroke design

62 keys, including Help key and 4 special
function keys

International character set

29 graphics keys

Programming

Features:

Built-in ATARI BASIC programming language
Software compatibility with all ATARI 65XE and
800XL Computers

RAM disk storage with ATARI DOS 2.5

Input/Output:

Software cartridge slot

TV output

Monitor output

2 controller ports

Serial I/O connector port

Enhanced Cartridge Interface

Power Supply:

1 Amp at 5 Volts DC

4 »

<»

4 »

<»

120

H. Accessing the Full RAM
Potential of the 130XE

The 130XE contains 131,072 bytes of Random Access Memory (RAM):
twice as much memory as the ATARI 65XE or the 800XL Computer.

The extra 65,536 bytes of RAM is transparent to the user in most
instances. Software programs may use the extra memory to store
larger databases. And if you use an ATARI 1050 Disk Drive with
ATARI DOS 2.5, you can use the extra memory as a RAMDISK—a
very fast disk drive. (For more information on the 130XE and the DOS
2.5 RAMDISK, see the DOS 2.5: ATARI 1050 Disk Drive Owner’s
Manual.)

However, you can access and use the extra 65,536 bytes of RAM with
ATARI BASIC through a “bank switching” method. The two processor
chips inside the 130XE—the 6502 central processor and the ANTIC
video processor—were designed to access only 65,536 bytes of RAM.
When the bank switching method is used, the computer is coerced
into using more memory. Bank switching turns off one 16K section of
RAM and uses some of another section in its place. In the 130XE, the
second bank of memory is located from memory location 16384 to
32767 in the memory map (in hexadecimal, the numbers $4000 to
$7FFF). By changing the bank switch, the computer can select which
bank of memory will occupy that 16K area.

The bank switch is located in memory location 54017. This location is
used as the port B address of the 6520 Peripheral Interface Adapter
chip, which controls the computer’s input and output. Half of this
memory location was used by the computer previously.

Bits 4 and 5 select which of the computer’s processors can access
the extra bank. Normally the bits are set to a 1. (Bit 4 enables the CPU
banking and Bit 5 enables the Video banking.) By changing one bit to a
0, the 6502 processor gains access to the extra RAM, and the other
bit gives access to the ANTIC video chip. Changing both bits lets both
processors use the extra memory.

Bits 2 and 3 control which section of the extra memory is used. There
are four possible combinations of the two bits, and four different 16K
memory sections from which to choose.

Normally, memory location 54017 contains a 193. By using the BASIC
language POKE command you can modify this memory location to
switch the extra RAM. For example, POKE 54017, 225 selects the first
section of extra RAM and makes that section available to the 6502
chip (but not to the ANTIC video chip).

The formula for selecting a bank of memory in the 130XE is:

POKE 54017,. 193 + 4*fiDDBESS + 16*MODE

TABLE OF VALUES

ADDRESS SECTION OF MEMORY

0 0 to 16383

1 16384 to 32767

2 32768 to 49151

3 49152 to 65535

MODE

6502 ACCESS

Extra

Normal

Extra

Normal

ANTIC ACCESS

Extra

Normal

MEMORY LOCATION 54017

Bit #:

Value:

128

(If set)

Video

Bank

CPU

Bank

MSB

Bank

LSB

Enable Enable
(VBE) (CBE)

Bits 0, 6, 7, 1 should always be set.

If VBE or CBE is set, corresponding accessing is to normal. If 0, any
access to address $4000-$7FFF is to the extra set by value of bank
bits.

122

I.Connector Pinout
Specifications

SERIAL I/O (PERIPHERAL) PORT

1. Clock Input

2. Clock Output

3. Data Input

4. Ground

5. Data Output

6. Ground

7. Command

8. Motor Control

9. Proceed

10. + 5/Ready

11. Audio Input

12. +12V

13. Interrupt

CARTRIDGE SLOT

ABCDEFHJKLMNPRS

12 3 4

5 6 7

1. S4

A. RD4

2. A3

B. GND

3. A2

C. A4

4. A1

D. A5

5. AO

E. A6

6. D4

F. A7

7. D5

H. A8

8. D2

J. A9

9. D1

K. A12

10. DO

L. D3

11. D6

M. D7

12. S5

N. All

13. +5V

P. A10

14. RD5

R. R/W

15. CCTL

S. B02

123

ENHANCED CARTRIDGE INTERFACE (ECI)

A B C D E F H

1 2 3 4 5

6 7

A. Reserved

1. EXSEL

B. IRQ

2. RST

C. HALT

3. D1XX

D. A13

4. MPD

E. A14

5. Audio

F. A15

6. REF

H. GND

7. + 5V

MONITOR JACK

1. Composite Luminance

2. Ground

3. Audio Output

4. Composite Video

5. Composite Chroma

124

POWER ADAPTER PLUG

1. +5V

2. Shield

3. Ground

4. +5V

5. Ground

6. +5V

7. Ground

CONTROLLER PORT

1. (Joystick) Forward Input

2. (Joystick) Back Input

3. (Joystick) Left Input

4. (Joystick) Right Input

5. B Potentiometer Input

6. Trigger Input

7. +5V

8. Ground

9. A Potentiometer Input

125

126

127

128

addition function, 48
alphanumeric variables, 45
arrow keys, 16, 31, 47, 48, 49
ATARI BASIC (see BASIC)
Audio-Visual Test, 10
auto repeat, 29

BASIC

built-in programming
language, 21-22, 23
disabling the language, 12, 21
bent arrow, 40
blank lines, 32
in programs, 38
blank spaces, 31-32
Break key, 11, 14, 34, 41, 66, 72
bugs, 57
BYE, 9, 12, 21
byte, 42-43

Caps key, 15, 17, 29-30, 31
caret, 48

caring for your computer, 8
cartridges

loading, 11-12, 24
software, 23
Clear key, 31,40

clearing the computer’s memory, 35
clearing the screen, 31,40
colon, 42
COLOR, 73, 74-75
color registers, 69

changing colors in, 71, 73, 74-75
designating, 73, 75
colors, 68-69
comma

in numbers, 47

with PRINT statements, 41-42
commands
COLOR, 73, 74-75
consolidating on one line, 42, 62
DIM, 43, 44, 45, 46
DRAWTO, 73-74
END, 56, 65, 66
FOR-NEXT, 57-63, 66, 68
FRE, 42-43
GOSUB-RETURN, 68
GOTO, 41,46, 55, 56, 66, 72
IF-THEN, 52, 55-57

INPUT, 43, 44, 53, 56
INT, 51
LIST, 35, 36
NEW, 35
PLOT, 73
POKE, 19

PRINT, 37, 38, 39, 40, 41, 42, 43,
44, 71, 72

PRINT #6;, 71, 72, 73
READ-DATA, 68
REM, 46
hND, 50-52
RUN, 36

SETCOLOR, 69, 71, 72, 73, 74, 75
SOUND, 65, 66
STEP, 59-60
TRAP, 56, 62, 68
compatibility, 23
Control key, 13, 15
for graphic symbols, 17, 30-31
for international characters, 19
with arrow keys, 16, 31
with Caps key, 16, 17, 31
with Clear key, 31,40
with Delete Back Space key, 16, 32
with Insert key, 16, 31
with Tab key, 33
with 1 key, 15, 40
with 2 key, 15
with 3 key, 15
counting loop, 57-63
cursor control, 31

DATA (see READ)
default color, 69, 71 73, 75
default luminance, 70
delay loop, 61-63

Delete Back Space key, 14, 16, 32
deleting
lines, 32

program lines, 38
spaces, 32

DIM (dimensioning), 43, 44, 45, 46

disk drive, 23, 24, 25

Disk Operating System, 12, 21

display screen, 25

distortion, 65-66

division sign, 49

Down Arrow key, 16, 31

DRAWTO, 73-74

dummy variable, 51

129

END, 56, 65, 66

Enhanced Cartridge Interface (ECl), 2
erase

computer’s memory, 35
program lines, 38
screen, 31

spaces and lines, 32
Error message, 29, 35, 37-38, 44 , 46 ,
56, 68

Escape key, 14, 34, 40
expansion (see ECl)
exponent, 47-48

FOR, 58

FOR-NEXT, 57-63
nested FOR-NEXT loops, 62
with SOUND, 66, 68
FRE, 42-43
frequency, 65

garbage error, 37
GOSUB-RETURN, 68
GOTO, 41, 46, 55, 56
to maintain graphics screen
display, 72
with SOUND, 66
graphic symbols, 17, 30-31, 40
graphics capabilities, 68-76
graphics modes, 68
mode 0, 69, 72
mode 1, 70-72, 73
mode 2, 70-72, 73
mode 3, 73-75
mode 5, 75-76
mode 7, 75-76

Help key, 9, 11, 14, 34

IF-THEN, 52, 55-57
increments in counting loops, 59-60
infinite loops, 41, 50, 55, 56
INPUT, 43, 44, 53, 56
inserting
blank lines, 32
blank program lines, 38

blank spaces, 31-32
program lines, 36
Insert key, 15, 16, 31, 32
installation of your computer, 5-8
instruction line
limit, 29, 39
numbering, 35, 36
INT, 51

international characters, 19
Inverse Video, 33, 40
to change colors in graphics
modes, 71, 73
to test keyboard, 11

joystick, 26

Keyboard Test, 11
keys, descriptions of, 13-16

Left Arrow key, 16, 31, 48

line breaks, 39

line numbering, 35, 36

LIST, 35, 36

logical line, 39

loop

counting, 57-63
delay, 61-63

FOR-NEXT, 57-63, 66, 68
GOTO, 41,46, 55, 56, 66, 72
infinite, 41, 50, 55, 56
lowercase, 29-30
to change colors in graphics
modes, 71, 73
luminance, 69, 70

math functions
addition, 48
division, 49
multiplication, 49
order of execution, 49-50
subtraction, 48
math programs, 53
memory, 9-10, 23, 35, 36, 42-43
Memory Test, 9-10, 11
minus sign, 47, 48
modem, 26

130

monitor, 25
multiplication sign, 49
musical notes, 67-68

nested FOR-NEXT loops, 62
NEW, 35
NEXT, 58
(see FOR-NEXT)
numbers, 47

numeric variables, 45, 52, 55, 58

Operating System, 23

Option key, 9, 12, 14, 21, 34

order of mathematical functions, 49,-50

parentheses

for order of mathematical
functions, 49-50
with RND, 51

peripherals, 23, 24, 25, 26

pitch, 65, 67

pixel, 73

PLOT, 73

plus sign, 48

POKE, 19

PRINT, 37

abbreviation for (?), 39
in graphics modes, 71, 72
to clear screen, 40
to create blank lines, 38
two statements on one line, 42-43
with colon, 42
with comma, 41-42
with graphic symbols, 40
with semicolon, 42
with string variables, 44
PRINT #6;, 71, 72, 73
printer, 26

program recorder, 23, 24, 26

question mark, 44
abbreviation for PRINT, 39
Question Mark key, 49
quotation marks
to clear screen, 40
with PRINT, 37, 40

RAM, 9, 10, 36, 42, 43
random numbers, 50-52
READ-DATA, 68
register

color, 69, 71, 73, 74, 75
sound, 65
REM, 46

Reset key, 9, 11, 14, 34, 72
RETURN (see GOSUB)

Return key, 15, 35

Right Arrow key, 16, 31, 48, 49

RND, 50-52

ROM, 9, 10, 23

RUN, 36

scientific notation, 47-48
screen display
format, 39

maintaining a graphics display, 72
stopping the LIST display, 40
Select key, 9, 14, 34
Self Test, 9-11
semicolon, 42, 44
SETCOLOR, 69, 71, 72, 73, 74-75
Shift key, 13, 17, 30
with Caps key, 17
with Clear key, 31, 40
with Delete Back Space key, 17, 32
with Insert key, 17, 32
with Right Arrow key, 48
with Tab key, 33
software

audiocassettes, 23, 24
built-in, 23

cartridges, 11-12, 23, 24
commercial, 23
compatibility, 23
diskettes, 23, 24
storing, 24, 25, 26
user-written, 21, 23-24
SOUND, 65-66
sound capabilities, 65-68
Start key, 9, 14, 34
starting point in counting loops, 59
STEP, 59-60

stopping point in counting loops, 59
stopping the screen display, 40
storing software, 24, 25, 26
string variables, 43, 44, 45, 55

131

subroutine, 68
subtraction function, 48

Tab key, 33
clear tabs, 33
set tabs, 33
test programs, 9-11
text mode, 69, 70
text window, 70, 72
THEN (see IF-THEN)

TRAP, 56, 62, 68

Up Arrow key, 16, 31,47, 48
uppercase, 29-30

to change colors in graphics
modes, 71, 73

variables, 43
dummy, 51

in SOUND commands, 66-67, 68
numeric, 45, 52, 55, 58
string, 43, 44, 45, 55
voice, 65

volume, 65, 66, 67

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